§ =42.= Isaac of Holland and a countryman of the same name, probably his son, are said to have been the first Dutch alchemists. They are supposed to have lived during the fifteenth century, but of their lives nothing is known. Isaac, although not free from superstitious opinions, appears to have been a practical chemist, and his works, which abound in recipes, were held in great esteem by Paracelsus and other alchemists. He held that all things in this world are of a dual nature, partly good and partly bad. “. . . All that God hath created good in the upper part of the world,” he writes, “are perfect and uncorruptible, as the heaven: but whatsoever in these lower parts, whether it be in beasts, fishes, and all manner of sensible creatures, hearbs or plants, it is indued with a double nature, that is to say, perfect, and unperfect; the perfect nature is called the Quintessence, the unperfect the Feces or dreggs, or the venemous or combustible oile. . . . God hath put a secret nature or influence in every creature, and . . . to every nature of one sort or kind he hath given one common influence and vertue, whether it bee on Physick or other secret works, which partly are found out by naturall workmanship. And yet more things are unknown than are apparent to our senses.”[57] He gives directions for extracting the Quintessence, for which marvellous powers are claimed, out of sugar and other organic substances; and he appears to be the earliest known writer who makes mention of the famous sulphur-mercury-salt theory. [57] _One hundred and Fourteen Experiments and Cures of the Famous Physitian Theophrastus Paracelsus, whereunto is added . . . certain Secrets of Isaac Hollandus, concerning the Vegetall and Animall Work_ (1652), p. 35. Bernard Trévisan (1406-1490). § =43.= =Bernard Trévisan=, a French count of the fifteenth century, squandered enormous sums of money in the search for the Stone, in which the whole of his life and energies were engaged. He seems to have become the dupe of one charlatan after another, but at last, at a ripe old age, he says that his labours were rewarded, and that he successfully performed the _magnum opus_. In a short, but rather obscure work, he speaks of the Philosopher’s Stone in the following words: “This Stone then is compounded of a Body and Spirit, or of a volatile and fixed Substance, and that is therefore done, because nothing in the World can be generated and brought to light without these two Substances, to wit, a Male and Female: From whence it appeareth, that although these two Substances are not of one and the same species, yet one Stone doth thence arise, and although they appear and are said to be two Substances, yet in truth it is but one, to wit, _Argent-vive_.”[58] He appears, however, to have added nothing to our knowledge of chemical science.