Some physicians have doubted respecting secret poison[103]; and others have only denied that its effects can with certainty be regulated to a fixed time[104]. I agree in opinion with the latter; but the former can be confuted by many examples both of ancient and modern times; for that the ancients were acquainted with this kind of poison, can be proved by the testimony of Plutarch, Quintilian, and other respectable authors. We are told by Plutarch, that a slow poison, which occasioned heat, a cough, spitting of blood, consumption, and a weakness of intellect, was administered to Aratus of Sicyon[105]; and Quintilian in his Declamations, speaks of this poison in such a manner as proves that it must then have been well known[106]. It cannot be said that such an invention was too great for that period, or that it required more knowledge of chemistry than any one possessed; for the Indians in America are acquainted with a most perfect poison of this kind, and can employ it with so much skill, that the person to whom it is given cannot guard against the treachery, even with the utmost precaution, but infallibly dies, though in a lingering manner, often after the expiration of some years[107]. Theophrastus speaks of a poison which could be moderated in such a manner as to have effect in two or three months, or at the end of a year, or two years; and he remarks that the death, the more lingering it was, became the more miserable. This poison was prepared from aconitum, a plant which, on that account, people were forbidden to have in their possession, under pain of capital punishment[108]. He relates also, that Thrasyas had discovered a method of preparing from other plants a poison which, given in small doses of a drachm, occasioned an easy but certain death, without any pain, and which could be kept back for a long time without causing weakness or corruption. This Thrasyas, whose scholar Alexias carried the art still further, was a native of Mantinea, a city in Arcadia, and is celebrated by Theophrastus on account of his abilities, and particularly his knowledge of botany; but those are mistaken who ascribe to him the discovery of secret poison.