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Amatus Lusitanus discovered valves in veins and arteries.

by David Hashavit

From HaLapid, Winter 2006

Amatus Lusitanus (1511-1568) was born to a family of crypto-Jews in the city of Castelo- Branco as João Rodrigues de Castelo-Branco. In 1497[1] his family had been forcibly converted to Christianity, all historical evidences of the family were lost. We assume that their former family name was "Haviv," a well known Jewish family in Spain. He studied Medicine and Botany in the University Of Salamanca, Spain.  After finishing his studies he returned to Portugal to practice his profession but he had to leave, frightened by the Inquisition, and traveled to Antwerp, about 1533. There he worked as a botanist and acquired phenomenal knowledge in herbal medicine as he continued to work as a physician. Among his patients were the Mayor of Antwerp, the Portuguese Consul and the well  known Doña Gracia [2]. 

Eventually he left Antwerp and went to Ferrara, Italy to teach medicine as a lecturer in the local university. There he apparently changed his name to Amatus (translation of "Haviv" – lovable, likable in Hebrew) Lusitanus (The Portuguese).   

Some years later he moved to Ancona, where he waited for permission to transfer to Ragusa (nowadays, Dubrovnik, Croatia). Meanwhile, he treated the sister of Pope Julius III. While there, his house was burnt and all his writings and papers were ruined. Finally, Amatus moved to Ragusa but he did not stay there long. He moved again to Salonika, Greece, then part of the Ottoman Empire. There he returned to Judaism.

As a physician he treated all people, wealthy and poor. In 1568 he died while treating patients during the plague. His burial place is not known.      

Amatus Lusitanus published books of medical botany, Index Dioscoridis and 7 Centuria1. Each volume contains de

scriptions of hundreds of different case histories that Amatus had treated, with commentaries and discussions. Among the medical descriptions he included moral and medical advice as well as the Jewish Physicians Oath [3]. (See page 13)

Amatus’ Discovery

There's a reasonable basis to assume that it was Dr. Amatus who first discovered the "Blood circulation" phenomena. There is no doubt that he discovered the valves in the veins, which enable blood to flow from the arms and legs towards the heart but disable flow in the opposite direction. This discovery contradicted the conventional belief of the time that the blood flows from the heart via the arteries as well as the veins. It is obvious that this hypothesis was supported by the fact that the network of arteries and veins becomes thinner and thinner as they get farther from the heart. It was also assumed that the networks are not connected, so the blood cannot pass from one network to the other. (The microscope was not yet invented, so one could not view capillary arteries without aid.)

Dr. Amatus Lusitanus described in the  Centuria I,  paragraph (Curatio) 513, how, in 1547, he performed an experiment before some scholars from the University of Ferrara. He blew air into the lower part of the azygos, and showed that the vena cava would not be inflated. It was not possible for the air to escape because of the valve or operculum mentioned.  When  it is clear that if air cannot pass out of the azygos into the vena cava, it is all the more certain that blood, much thicker than air, could not flow through.

In the audience was "the admirable anatomist” Canano4, to whom the discovery of the valves was attributed later by mistake.

The discovery of the valves was also attributed to Fabricius5,   the teacher of Harvey6, who later discovered the circulation of the blood. As a proof they show Fabricius' book: De  Venarum Ostiolis, 1603, where he discusses the valves of the veins with detailed illustrations. It is interesting to note that Fabricius continued to claim that the blood flow direction was from the heart. Fabricius didn't understand the function of the valves.

There is no direct evidence that Amatus knew of the blood circulation phenomena, although indirect evidence can be shown, which I outline below.

1. The demonstration of the vein before respected audience and blowing air inside it, could have other targets. Some questions arise here.  First, why did Amatus perform this demonstration and why before such a respected forum? My assumption is that Amatus hoped that at least one of the respected scholars would understand the implication of blood flow in one direction, as opposed to the conventional opinion, and would ask for explanations.  If it would have occurred, Amatus could discuss it deeply and thoroughly and no one could accuse  him of introducing a heretical opinion, even if he would lose the fame of the discovery.

          A second question that arises is did he find the valves in the veins randomly? My assumption is that Amatus did not discover the valves by accident, but concluded their existence logically, after he assumed the "blood circulation" phenomena.  Since the existence of valves in the heart had already been discovered by Galen6 in the second century, he assumed they existed to avoid flow of blood backwards. Amatus expanded the theory when he realized that there should be a mechanism which should avoid ''falling” of blood in the veins of the leg.

To emphasize, his experiment of blowing air inside a vein or an artery would only be performed if he thought that he might discover something new.  

2.  Amatus Lusitanus was an innovator indeed, and he was ready to challenge the ancient beliefs, but only when he had clear proof. He was ready to deviate from his master when his own experience found Galen in error.

He described the optic nerves as not being hollow, and the cavity of the human uterus as not being divided. He demonstrated the structure of the mammary gland and showed that this explained why it is frequently necessary in suppuration of this organ to make multiple incisions7. One of his most important contributions was in the treatment of emphysema. It was the custom to make the incision for draining high up in the chest. On the basis of the anatomical studies he urged that the opening should be made in the lower intercostals spaces, so as to secure best drainage and yet do no harm to the diaphragm. [2]

Yet, in the matter of blood circulation, Amatus did not feel safe in discussing it, so he only demonstrated his findings.  

3.  The following point is a little bit misty. Many researchers, who are anxious to bring their theories before the public do so only late in life. For example, Nicolaus Copernicus (14973-1543) published his heliocentric theory in his book: De Revolutionibus Orbium Coelestium, in Nuremberg 1543, although it was completed before 1533. Charles Darwin (1809-1882) postponed publishing of his book On the Origin of Species by Means of Natural Selection until 1859. Even William Harvey postponed publishing his blood circulation theory many years after he had spoken about it in his lectures. Although he was a high ranking personal physician to the king, he was very apprehensive as he himself testified:

"[It] is of so novel and unheard-of character, that I not only fear injury to myself from the envy of a few, but I tremble lest I have mankind at large for my enemies, so much does wont and custom, that has become as another nature, and doctrine once sown and that has struck deep root and rested from antiquity, influence all men."

Is it possible that Amatus Lusitanus postponed the publication of his theory, and his sudden death  in Salonika in 1568 prevented it? It is known that in 1555 his house in Ancona, was robbed and burnt, [5] so no evidence about his knowledge of blood circulationb remains.

 4. Amatus' Judaism: Although Amatus was a Christian, it was known that he was a New Christian, so his colleagues suspected that he was a hidden Jew and they did not trust him. The brutal behavior of Matthioli8 shows this point. Such behavior would not be forgiven if it was directed towards an Old Christian9. Amatus was very careful and would not dare to challenge the Inquisition, so it is doubtful that Amatus would publicly sepouse a suspicious theory that was contrary to the opinions of the ancients and the government. Amatus' Judaism caused his colleagues to suppress his contribution to research on blood circulation. We already mentioned that the discovery of the valves had been attributed to Canano and even Harvey attributed it to Fabricius.  


Although Amatus discovered the existence of valves in the veins, neither he, nor any other scholar dared to explain the real task of the valves, for it contradicted Galen's theory. Even Fabricius, Harvey's teacher, would claim that the blood flows in the direction counter to that which the valves prevent. Osler comments in wonder, four hundreds years later:

"But here comes the mystery. How Fabricius, a man who did such work, how a teacher of such wide learning and such remarkable powers of observation, could have been so blinded, as to overlook the truth which was tumbling out, so to speak, at his feet?"[6]

It is beyond the scope of this paper to discuss the role of the Inquisition in impeding scientific investigation into new theories. Few people were as brave as was Galileo Galilee (1564-1642). [7]  Eventually even he was forced to retract his theories and state that the Earth was the center of the universe. Certainly a hidden Jew like Dr. Amatus Lusitanus could not have chanced a confrontation with the authorities of the day.

Isn't it time to admit that he is the real discoverer of blood circulation and to award him the appropriate respect?

End Notes

1. In the National Library in Jerusalem (Edelstein collection) one can view an exemplar of all the Centuria,  in a wonderful situation.

 2. One of Amatus' relatives is Joseph Oef , a name with the same meaning.

 3. In some editions the paragraph is numbered 51, in other as 52.

 4. Giovanni Battista (Giambattista) Canano, 1515-1579, lecturer of Medicine and Anatomy at the University of Ferrara. He was a personal physician to Pop Julius II. Canano published  the book:  Musculorum humani corporis picturata dissection in Ferrara, 1541.

5. Hieronymus Fabricius (1537-1619), a lecturer in medicine in the University of Padua. He was practicing anatomy and surgery and investigated the blood systems. Since 1574, he demonstrated, in his lectures, the action of the valves in the veins.

6. William Harvey (1578-1657). The discovery of the blood circulation phenomena is usually related to him. He was physician in the court of King James I and personal physician to King Charles I. 

7. There is a claim that the phenomena was discovered, as a matter of fact, by Erasistratus  (303-250 B.C), a Greek physician, who lived in Syria and investigated the brain and nerves.

8. I must remind the readers that neither the magnifying glass nor microscopes were used in those days.

9.  Pietro Andrea Matthioli (1501-1577), Botanist and a personal physician  to the King of Austria. Amatus found some errors in the  Index Dioscoridis of  Matthioli.

10.  The researchers assume that Matthioli's  behavior caused Amatus to leave Ferrara and move to Ragusa.


1. Benveniste Arthur, “The Forced Conversion of the Jews of  Portugal,”  HaLapid, Society for Crypto-Judaic Studies, 1997.

2.  Friedenwald Harry, “The Jews and Medicine, Essay XXV ,”  Amatus Lusitanus, Baltimore, The Johns Hopkins press, 1944

3. last entrance: 12/12/2005

4. Sloan Dolores J., “Ferrara: Spiritual Haven for Conversos in the Early Renaissance, “ HaLapid, Society for Crypto-Judaic Studies, 1999

          5. Friedenwald Harry, Medical Works of Amatus Lusitanus, in Homenagen ao Doutor João Rodrigues de Castelo Branco (Amatus Lusitanus), pp. 180-181, Imprense de Coimbra

6. Osler William, “The Growth of Truth,”  Harverian Oration, p. 17, 1906

7. Drake Stillman, Galileo, Oxford University Press, 1980