Erasistratus (gr. Ἐρασίστρατος, Erasistratos), one of the most celebrated physicians and anatomists of antiquity, is generally supposed to have been born at Iulis in the island of Ceos (Suidas, s. v. Ἐρασίστρ.; Strab. x. 5, p. 389, ed. Tauchn.), though Stephanus Byzantinus (s. v. Κῶς) calls him a native of Cos, Galen of Chios (Introd. c. 4, vol. xiv. p. 683), and the emperor Julian of Samos. (Misopog. p. 347.) Pliny says he was the grandson of Aristotle by his daughter Pythias (H. N. xxix. 3), but this is not confirmed by any other ancient writer; and according to Suidas, he was the son of Cretoxena, the sister of the physician Medius, and Cleombrotus ; from which expression it is not quite clear whether Cleombrotus was his father or his uncle. He was a pupil of Chrysippus of Cnidos (Diog. Laërt. vii. 7. § 10, p. 186; Plin. H. N. xxix. 3 ; Galen, de Ven. Sect. adv. Erasistr. c. 7, vol. xi. p. 171), Metrodorus (Sext. Empir. c. Mathem. i. 12, p. 271, ed. Fabric.) and apparently Theophrastus. (Galen, de Sang. in Arter. c. 7, vol. iv. p. 729.) He lived for some time at the court of Seleucus Nicator, king of Syria, where lie acquired great reputation by discovering the disease of Antiochus, the king's eldest son, probably 294 BC. Seleucus in his old age had lately married Stratonice, the young and beautiful daughter of Demetrius Poliorcetes, and she had already borne him one child. (Plut. Demtetr. c. 38; Appian, de Rebus Syr. c. 59.) Antiochus fell violently in love with his mother-in-law, but did not disclose his passion, and chose rather to pine away in silence. The physicians were quite unable to discover the cause and nature of his disease, and Erasistratus himself was at a loss at first, till, finding nothing amiss about his body, he began to suspect that it must be his mind which was diseased, and that he might perhaps be in love. This conjecture was confirmed when he observed his skin to be hotter, his colour to be heightened, and his pulse quickened, whenever Stratonice came near him, while none of these symptoms occurred on any other occasion; and accordingly he told Seleucus that his son's disease was incurable, for that he was in love, and that it was impossible that his passion could be gratified. The king wondered what the difficulty could be, and asked who the lady was. " My wife," replied Erasistratus; upon which Seleucus began to persuade him to give her up to his son. The physician asked him if he would do so himself if it were his wife that the prince was in love with. The king protested that lie would most gladly; upon which Erasistratus told him that it was indeed his own wife who had inspired his passion, and that he chose rather to die than to disclose his secret. Seleucus was as good as his word, and not only gave up Stratonice, but also resigned to his son several provinces of his empire. This celebrated story is told with more or less variation by many ancient authors, (Appian, de Rebus Syr. c. 59-61; Galen, de Praenot. ad Epig. c. 6. vol. xiv. p. 630; Julian, Misopog. p. 347, ed. Spanheim; Lucian, de Syria Dea, §§ 17, 18; Plin. H. N. xxix. 3; Plut. Demetr. c. 38; Suidas, s. v. Ἐρασίστρ.; Jo. Tzetz. Chil. vii. Hist. 118; Valer. Max. v. 7), and a similar anecdote has been told of Hippocrates (Soranus, Vita Hippocr. in Hippocr. Opera, vol. iii. p. 852), Galen (de Praenot. ad Epig. c. 6. vol. xiv. p. 630), Avicenna (see Biogr. Dict. of the Usef. Knowl. Soc.), and (if the names be not fictitious) Panacius (Aristaen. Epist. i. 13) and Acestinus. (Heliod. Aethiop. iv. 7. p. 171.) If this is the anecdote referred to by Pliny (l. c.), as is probably the case, Erasistratus is said to have received one hundred talents for being the means of restoring the prince to health, which (supposing the Attic standard to be meant, and to be equal to 243l. 15s.) would amount to 24,375l.--one of the largest medical fees upon record.

Very little more is known of the personal history of Erasistratus : he lived for some time at Alexandria, which was at that time beginning to be a celebrated medical school, and gave up practice in his old age, that he might pursue his anatomical studies without interruption. (Galen, de Hippocr. et Plat. Deer. vii. 3, vol. v. p. 602.) He prosecuted his experiments and researches in this branch of medical science with great success, and with such ardour that he is said to have dissected criminals alive. (Cels. de Medic. i. praef. p. 6.) He appears to have died in Asia Minor, as Suidas mentions that lie was buried by mount Mycale in Ionia. The exact date of his death is not known, but he probably lived to a good old age, as, according to Eusebius, he was alive B. C. 258, about forty years after the marriage of Antiochus and Stratonice. He had numerous pupils and followers, and a medical school bearing his name continued to exist at Smyrna in Ionia nearly till the time of Strabo, about the beginning of the Christian era. (Strab. xii. 8, sub fin.) The following are the names of the most celebrated physicians belonging to the sect founded by him : Apoemantes (Galen, de Venae Sect. adv. Erasistr. c. 2, vol. xi. p. 151), Apollonius Memphites, Apollophanes (Cael. Aurel. de Morb. Acut. ii. 33, p. 150) Artemidorus, Charidemus, Chrysippus, Heraclides, Hermogenes, Hicesius, Martialis, Menodorus, Ptolemaeus, Strato, Xenophon. He wrote several works on anatomy, practical medicine, and pharmacy, of which only the titles remain, together with a great number of short fragments preserved by Galen, Caelius Aurelianus, and other ancient writers: these, however, are sufficient to enable us to form a tolerably correct idea of his opinions both as a physician and an anatomist. It is in the latter character that he is most celebrated, and perhaps there is no one of the ancient physicians that did more to promote that branch of medical science. He appears to have been very near the discovery of the circulation of the blood, for in a passage preserved by Galen (de Usu Part. vi. 12, vol. iii. p. 465) he expresses himself as follows :--" The vein arises from the part where the arteries, that are distributed to the whole body, have their origin, and penetrates to the sanguineous [or right] ventricle [of the heart]; and the artery [or pulmonary vein] arises from the part where the veins have their origin, and penetrates to the pneumatic [or left] ventricle of the heart." The description is not very clear, but seems to shew that he supposed the venous and arterial systems to be more intimately connected than was generally believed; which is confirmed by another passage in which he is said to have differed from the other ancient anatomists, who supposed the veins to arise from the liver, and the arteries from the heart, and to have contended that the heart was the origin both of the veins and the arteries. (Galen, de Hippocr. et Plat. Decr. vi. 6, vol. v. p. 552.) With these ideas, it can have been only his belief that the arteries contained air, and not blood, that hindered his anticipating Harvey's celebrated discovery. The tricuspid valves of the heart are generally said to have derived their name from Erasistratus ; but this appears to be an oversight, as Galen attributes it not to him, but to one of his followers. (De Hippocr. et Plat. Deer. vi. 6, vol. v. p. 548.) He appears to have paid particular attention to the anatomy of the brain, and in a passage out of one of his works preserved by Galen (ibid. vii. 3, vol. v. p. 603) speaks as if he had himself dissected a human brain. Galen says (ibid. p. 602) that before Erasistratus had more closely examined into the origin of the nerves, he imagined that they arose from the dura mater and not from the substance of the brain; and that it was not till he was advanced in life that he satisfied himself by actual inspection that such was not the case. According to Rufus Ephesius, he divided the nerves into those of sensation and those of motion, of which the former he considered to be hollow and to arise from the membranes of the brain, the latter from the substance of the brain itself and of the cerebellum. (De Appell. Part. &c. p. 65.) It is a remarkable instance at once of blindness and presumption, to find this acute physiologist venturing to assert, that the spleen (Galen, de Atra Bile, c. 7. vol. v. p. 131), the bile (id. de Facult. Natur. ii. 2, vol. ii. p. 78), and several other parts of the body (id. Comment. in Hippocr. "De Alim." iii. 14. vol. xv. p. 308), were entirely useless to animals. In the controversy that was carried on among the ancients as to whether fluids when drunk passed through the trachea into the lungs, or through the oesophagus into the stomach, Erasistratus maintained the latter opinion. (Plut. Sympos. vii. 1; Gell. xvii. 11, Macrob. Saturn. vii. 15.) He is also supposed to have been the first person who added to the word ἀρτηρία, which had hitherto designated the canal leading from the mouth to the lungs, the epithet τραχεῖα, to distinguish it from the arteries, and hence to have been the originator of the modern name trachea. He attributed the sensation of hunger to vacuity of the stomach, and said that the Scythians were accustomed to tie a belt tightly round their middle, to enable them to abstain from food for a longer time without suffering inconvenience. (Gell. xvi. 3.) The πνεῦμα, or spiritual substance, played a very important part both in his system of physiology and pathology: he supposed it to enter the lungs by the trachea, thence to pass by the pulmonary veins into the heart, and thence to be diffused throughout the whole body by means of the arteries (Galen, de Differ. Puls. iv. 2, vol. viii. p. 703, et alibi); that the use of respiration was to fill the arteries with air (id. de Usu Respir. c. l. vol. iv. p. 471); and that the pulsation of the arteries was caused by the movements of the pneuma. He accounted for diseases in the same way, and supposed that as long as the pneuma continued to fill the arteries and the blood was confined to the veins, the individual was in good health; but that when the blood from some cause or other got forced into the arteries, inflammation and fever was the consequence. (Galen, de Venae Sect. adv. Erasistr. c. 2. vol. xi. p. 153, &c.; Plut. de Philosoph. Plac. v. 29.) Of his mode of cure the most remarkable peculiarity was his aversion to bloodletting and purgative medicines : he seems to have relied chiefly on diet and regimen, bathing, exercise, friction, and the most simple articles of the vegetable kingdom. In surgery he was celebrated for the invention of a catheter that bore his name, and was of the shape of a Roman S. (Galen, Introd. c. 13. vol. xiv. p. 751.) Further information repecting his medical and anatomical opinions may be found in Le Clerc, Hist. de la Méd.; Haller, Biblioth. Anat. and Biblioth. Medic. Pract.; Sprengel, Hist. de la Méd.; and also in the following works, which the writer has never seen : Jo. Frid. Henr. Hieronymi Dissert. Inauy. exhibens Erasistrati Erasistrateorumnque Historinm, Jen. 1790, 8vo. ; F. H. Schwartz, Herophilus und Erasistratus, cine historische Parallele, Inaug. Abhandl., Würrzburg, 1826, 8vo..; Jerem. Rud. Lichtenstadt, Erasistratus als Vorgänger von Broussais, in Hecker's Annal. der Heilkunde, 1830, xvii. 153.