The first book written by indigenous people and produced in New Spain is the Libellus de Medicinalibus Indorum Herbis (Treatise on Indigenous Medicinal Herbs), which, as its name suggests, refers to with healing plants in the territory now known as Mexico. The book was written at the Colegio de la Santa Cruz in Tlatelolco, then on the outskirts of present-day Mexico City. This college was attended by the sons of the Mexica nobility and was directed by friar Jacobo de Grado, who sought funding from the Spanish crown with local data on herbal medicine. Martín de la Cruz was a prestigious ticitl due to his experience and extensive knowledge, even without formal education, based in Santiago Tlatelolco. He worked at the school attending sick students. He was commissioned to write a text on local remedies; the manuscript was most likely written in Nahuatl. Juan Badiano, a native of Xochimilco in southern Mexico City, also had knowledge of traditional indigenous medicine and formal education in Latin and Spanish, and therefore collaborated with De la Cruz in translating the document into Latin and probably modified it to make it understandable to Spanish readers. Native artists, tlacuilos, drew the plants that illustrate the work, and students of the college, educated in Spanish, Greek and Latin, probably participated in drawing up the Libellus. It was in the royal library at El Escorial and it seems that it was transferred to Italy by Cardinal Barberini in around 1625. It was later moved to the Vatican and from there to Mexico, where it has been since 1990.

The Codex De la Cruz-Badiano18 describes 224 plants with 185 illustrations. The taxonomic identification of about half of the plants described in the Codex has been proposed, as well as their indigenous name, and their probable medical application. Bye and Linares19 of the Institute of Biology of the Universidad Nacional Autónoma de México (UNAM) confirm that approximately 60% of the plants identified in the codex grow spontaneously in the Basin of Mexico.

The Codex consists of 13 chapters, each generally in an anatomical sequence. Thus, the first chapter covers diseases of the head, the second diseases of the eyes, the third diseases of the ears, the fourth diseases of the nose, and so on. The eighth chapter includes, among other diseases, "podagra, popliteal pain and incipient contraction of the knees" and the ninth chapter, "diseases of the joints". Many of the plants initially listed, under what we can infer to be rheumatic diseases, have not been identified or are no longer in use as indicated in the Codex. I will only mention a few that are still used as treatment for rheumatic diseases. However, it seems appropriate to start, as an example of the descriptions in the Codex, with cocoa, a plant that is well known and used today, although not specifically for rheumatic diseases. The scientific name is Theobroma cacao,20 from the botanical family Malvaceae. The Nahua name is tlapalcacahuatl and the current common name is cocoa. It is described as a small tree with oblong leaves and flowers with pink petals. The use stated in the Codex "against the fatigue of those who administer the republic and hold public office" has obviously changed, although cocoa is still used as a stimulant and as a beverage drunk for pleasure almost everywhere in the world. At that time, it was restricted to the nobility.

These are the kind of descriptions used throughout the Libellus, albeit more extensive and with several of the indigenous words that defined them. For this review I will only mention some of the characteristics described in the Codex with the above-mentioned criteria: they were used for rheumatic diseases (or for pains that nowadays could be attributed to rheumatic diseases), they are identified, and they are still used with similar indications.

Texochitl yamanqui has the scientific name Selaginella lepidophylla,21 of the family Selaginellaceae; its current name is “flor de peña” or “doradilla”. The use in the Codex is for "contraction of the knees", but its current use is "for rheumatism”.

Tzitzicton, scientific name Gymnosperma glutinosum,22 of the botanical family Asteraceae. Its current common name is tatalencho or escobilla. The use recorded in the Codex is also for "incipient contraction of the knees" and has been maintained to some extent, as today a decoction of the herb is taken and rubbed in to relieve joint pain.

Quauhtzitzicaztli, scientific name Urera martiniana,23 of the botanical family Urticaceae. The current common name is chichicaztli. Its use in joint disease as designated in the Codex has continued.

Tetzitzicaztli, scientific name Cnidoscolus sp.,24 botanical family Euphorbiaceae. Current common name is chichicaztli, “mala mujer” or nettle. The use as recorded in the Codex is for patients with joint disease has continued.

Tetzitzicaztli, scientific name Cnidoscolus sp.,25 of the botanical family Rosaceae. The current common name is capulin. In the Codex it is indicated for joint disease. Nowadays it is used more generally used for the myoarticular system by massaging the whole body, including the joints, in the temazcal bath (traditional steam bath used at that time and still in use today).

The Codex was also produced at the Colegio de la Santa Cruz de Santiago Tlatelolco, which, as we note above, was the most important centre for the sciences and arts during the early colonial period in New Spain. Fray Bernardino de Sahagún was the main promoter of the activities of the college, where the natural sciences, including Nahuatl medicine, were studied. It also taught Greek, Latin, and Spanish and what we would now call political science to indigenous people who came from the nobility. Fray Bernardino was born in the village of Sahagún, kingdom of León, in around 1500. He studied at the University of Salamanca between 1523 and 1528. He embarked from Cadiz for the so-called West Indies in 1529 and in 1536 he settled in Santiago Tlatelolco, where he was the main promoter of the college’s activities. He wrote sermons in the Nahuatl language and collected prayers and exhortations used by the indigenous people. In the wake of the plague that struck New Spain, he began his research into what the indigenous people did to treat such diseases. He travelled to various parts of the country and during these journeys he continued his work gathering information, primarily through questionnaires that he presented to the most knowledgeable of the local indigenous people. After returning to Tlatelolco in 1565, he was sent to the convent of San Francisco in Mexico, where he spent three years revising and organising his documents into the form they are known today. These manuscripts make up the Historia general de las cosas de la Nueva España, which is the Spanish text of the Florentine Codex, as the king's representative ordered Sahagún to translate the Nahua texts in 1575. Thus, the work we know today as the Florentine Codex was produced in Tlatelolco. Fray Bernardino died on 5 February 1590.

The Codex, now in the Biblioteca Medicea Laurenziana in Florence (Italy) (hence the name Florentine Codex) is a work written in 2 languages by Nahua co-authors (tlamatinime) and illustrated by skilled indigenous painters (tlacuiloque). Its complex manuscript and illustrations make the Codex as whole a work of art. It depicts a world about to disappear after the war of conquest and epidemics. The authors and artists who "decided to finish the work locked up in the college of Tlatelolco fought with brushes and nibs like warriors for life and against death… they made the world they inherited materialise, they created images to communicate what they saw in all its splendour through colour".26 The importance of the colour pigments in the manufacturing process of the Codex, the influence of the painters on the work, as well as the methods they used to prepare these pigments, have recently been highlighted, and these data have been related to the historical context.27

Sahagún's work consists of 12 books covering not only medicine but all aspects of the life and culture of the ancient peoples of central Mexico.28 However, in several of the books that comprise this work there are references to diseases and how to treat them. For example, the first book, which does not cover medicine or herbalism but rather the gods worshipped by the natives, describes the belief that certain illnesses derived from the cold, mainly in the mountains, referring to "gout of the hands or feet". Sick people with these ailments made vows to the gods of air, water, and rain, as described above in relation to Ehecatl and his cult in Cholula.16

Chapter VIII of the tenth book28 describes the medical activity of women or men: "the good physician is learned, a knower of the properties of herbs, stones, trees and roots, experienced in cures, his craft is to know how to set bones, to purge, to bleed, to cut, and to stitch, and finally to deliver from the gates of death". In this same tenth book, a chapter "diseases of the human body and of the medicines against them"29 is described with 72 entries. One entry notes joint puncture30 "for swellings or bulges of the knees it will be necessary to lance them, and thus the blood or aguadija will come out, and then a poultice made from the ground leaf of a certain herb called toloa will be applied". Remedies for "swellings and humours of the feet" are also described.

In line with the aim of this review, we shall focus on the eleventh book, which refers in clause 5 to the properties of medicinal herbs.31 There are 98 clauses referring to such herbs, their general characteristics and their indications. Of these, only 4 refer to rheumatic diseases. One herb is called cocotzauhqui xíhuitl, with the indication that drinking it "makes rheumatism run away".32 Another herb was called cococxíhuitl, which "purifies the throat from rheumatism and the chest". These 2 plants were also used for the management of coughs and to facilitate expectoration. There is another plant called quauhxoxoxouhqui: "the leaves and seeds ground all together and mixed with water and resin, washing the body with it combats gout; and when the gout has spread throughout the body and causes great pain, and the whole body is drying up, if it is washed with it or it is put all over the body mixed with resin, and feathered, with this it tames the pain; and also drinking the ground seed on an empty stomach and mixed with water tames the pain".33 They also used the maguey,34tlacámetl, a drink known as pulque, still very common today, especially in rural areas. It was used as a poultice mixed with resin for gout pain or mixed with other herbs drunk for various types of pain.

The following is an example of how herbal medicine was used with other resources in cases of rheumatic disease of the hand: xoxouhcapahtli seed was used with quetzalxoxoxouhqui leaves and yztauhyatl herb, crushed and boiled in water.35 In addition to the likely soothing effect of these plants, the patient was led to a hole where ants lived and instructed to "patiently tolerate your hands being bitten by ants". Therefore, in addition to herbal medicine, ant bite is described, whose venom contains formic acid and piperidine, which are substances with some antioxidant and anti-inflammatory effect.

Both the Codex De la Cruz-Badiano and Sahagún’s Codex describe other non-herbal remedies for the treatment of rheumatic diseases, such as that mentioned in the above paragraph, and others in which herbs were ground and mixed with animal substances (from scorpions or snakes), or with minerals. They also used physical remedies, such as massages in the steam bath called temazcalli.36,37

As we have already mentioned, many Spaniards who came to colonise New Spain were impressed by the efficacy of some indigenous medical resources, which came to the attention of the Spanish crown. For this reason, in 1570, Philip II, King of Spain, sent his personal physician, Francisco Hernández, to Mexico, who for 7 years gathered considerable knowledge about the country’s medicinal plants and collected a magnificent herbal collection.38 In 2015 in Mexico, the UNAM prepared and published the complete works of Francisco Hernández, in electronic and printed versions, gathering all the writings of the "protomédico general of all the Indies, islands and mainland of the Ocean Sea", on the occasion of the 500th anniversary of his birth.

Francisco Hernández was born in Puebla de Montalbán (Toledo) around 1517, studied medicine in Alcalá de Henares and undertook his professional work at the Spanish court and university. In January 1570, King Philip II proclaimed him “protomédico” of all the Indies and gave him detailed instructions on what he was to investigate in the New World. At that time, Spain and all Europe were closely watching what was new in America and its riches. There were new men, new customs, unknown plants, animals, and minerals; immense mountains, vast plains; seas, islands, and rivers of remarkable width, and soon the land offered gold, silver, precious stones, food, and medicine. The American pharmacopoeia spread rapidly across Europe. Many of the herbs and roots used by indigenous healers proved valuable in the European pharmacopoeia, so much so that they were praised by writers and poets of the time.

In Mexico, Spain was building a state organisation in its new territories on its own model. Military conquest gave way to civilian presence and gradually left the field open to physicians, pharmacists and naturalists, whose reports clearly showed the essential need to learn about indigenous herbal medicine. Therefore, the instructions issued by the king to Francisco Hernandez read39 "It is hereby ordered that you, Doctor Francisco Hernández, our physician… First, that with the first fleet to leave these realms for New Spain you shall embark…, you shall consult, wheresoever you go, all the doctors, medicine men, herbalists, and Indians… and thus gather information generally about herbs, trees and medicinal plants in whichever province you are at the time".

During years of constant work, not only in the capital of New Spain but also in several of its provinces, Hernández completed a remarkable compilation work with his medical informants in these regions, who even 50 years after the conquest were still practising the medicine inherited from their ancestors. It is likely that such information was richer and more authentic in the Mexican province, as it is conceivable that medical ideas and practices from Spain had initially permeated the capital.

Doctor Hernández returned to Spain with extensive writings detailing many of his findings, which were handed over to the Spanish crown. Fortunately, he kept several originals and drafts. He died on 28 January 1587, having won over the newly discovered world with his medical and scientific vision.40,41

The works that remained in Hernández’ home are preserved to this day and allow us to learn about his work, as Philip II commissioned the Neapolitan physician Nardi Antonio Recchi to produce an abridged version. This work was deposited in the library of El Escorial, where it remained until it was consumed by fire during the fire of 1671. The manuscript material that Hernández kept in his home was dispersed over time; most of it ending up in the Jesuit convent in Madrid; other works ended up in private libraries, thanks to which they have been preserved.

This great work describes 3076 plants; 3000 of them are listed in Nahua names, the rest in other native languages. They were found in 1858 localities; their medical use, dosage and in many cases form of preparation is indicated in the work.42 One hundred and fifty-two chapters form the first book of the Historia de las plantas de Nueva España. The following paragraphs describe the order in which Hernández records in his Historia the data he obtained from his informants, from his travels around the country, often growing the plants himself and sometimes testing their effect on the natives and even on himself43:

• a

  Name of the plant; the indigenous name is noted by Hernández, with a second name that translates the plant’s meaning into Spanish, its medical action and similarity with another foreign plant.

• b

  The description of the specimen, which usually begins by specifying whether it is a herb or a tree.

• c

  On the “temperament” or “nature” of the specimen, heat, coldness, dryness, and humidity are referred to in different degrees.

• d

  Form of action. In the Historia about a thousand plants are described as cold; there are slightly fewer hot plants and fewer than a hundred warm plants. Both the nature and form of action were concluded from the theory of humours, then prevalent in European medicine, and not what we now understand as the mechanism of action.

• e

  Reference to the health problems that the plant is recommended to resolve.

• f

  Place where the plant grows. Characteristics of the soil and climate.

• g

  Special observations. Hernández’ observations about certain plants show discrepancies between his ideology, principally the theory of humours, and that of the indigenous peoples. The most frequent differences lie in the treatment of fever.

Indeed, the most frequent problem lies in the indigenous treatment of fevers, which used to be with remedies that Hernández described as hot. According to his thinking, fever should be treated with medicines he described as cold, which did not always coincide with the indigenous treatments. Francisco Hernández knew and applied the theory of humours, inherited from Greek and Roman medical culture. The humours are referred to 13 times in the 152 chapters that make up the first book of the Historia de las plantas de Nueva España. In this review we mention this theory of humours because of the importance attached to them by Hernández, but we indicate the relationship with the therapeutic resources used in pre-Hispanic Mesoamerica, which shows the cultural and medical syncretism in this work.

Examples of what we describe can be found in several texts, such as that which states that "the joints loaded with humours are joints that are hindered, which are relieved with the decoction of tzonpotónic",44 or that chichicahoazton "thins and makes the humours accumulated in the joints disappear".45 The “protomédico” explains the action of a cihuapatli "born in the warm lands of Yacapichtla - today's Yecapixtla de Morelos – which admirably resolves the humours that have penetrated the joints or the nerves ".46 In other words, the causal role according to the theory of humours and the therapeutic resource according to indigenous herbalism, as we mentioned, show the cultural and medical syncretism in Mesoamerica at that time.