“A plant,” says Jones of Nayland, “is a system of life, but insensitive and fixed to a certain spot. An animal hath voluntary motion, sense, or perception, and is capable of pain and pleasure. Yet in the construction of each there are some general principles which very obviously connect them. It is literally as well as metaphorically true, that trees have limbs, and an animal body branches. A vascular system is also common to both, in the channels of which life is maintained and circulated. When the trachea, with its branches in the lungs, or the veins and arteries, or the nerves, are separately represented, we have the figure of a tree. The leaves of trees have a fibrous and fleshy part; their bark is a covering which answers to the skin in animals. An active vapour pervades them both, and perspires from both, which is necessary for the preservation of health and vigour. The _vis vitæ_, or involuntary, mechanical force of animal life, is kept up by the same elements which act upon plants for their growth and support.”[2] [Footnote 1: CHAPMAN.] [Footnote 2: The reader of Berkeley will naturally turn to the Siris of that author—called by Southey in his life of Wesley “one of the best, wisest, and greatest men whom Ireland, with all its fertility of genius, has produced.” Vol. ii. 260., 2nd _Edit._] “Plants,” says Novalis, “are Children of the Earth; we are Children of the Æther. Our lungs are properly our root; we live when we breathe; we begin our life with breathing.” Plato also compared man to a Tree, but his was a physical similitude, he likened the human vegetable to a tree inverted, with the root above and the branches below. Antonio Perez allegorized the similitude in one of his epistles to Essex, thus, _unde credis hominem inversam arborem appellari? Inversam nostris oculis humanis et terrenis; rectam verò verè, viridemque, si radicem defixam habuerit in suo naturali loco, cœlo, unde orta._ And Rabelais pursues the resemblance farther, saying that trees differ from beasts in this, _qu'elles ont la teste, c'est le tronc, en bas; les cheveulx, ce sont les racines, en terre; et les pieds, ce sont les rameaulx, contremont; comme si un homme faisoit le chesne fourchu._ The thought that man is like a tree arose in the Doctor's mind more naturally when he first saw the representation of the veins and arteries in the old translation of Ambrose Paré's works. And when in course of time he became a curious enquirer into the history of her art, he was less disposed to smile at any of the fancies into which Doña Oliva Sabuco Barrera had been led by this resemblance than to admire the novelty and ingenuity of the theory which she deduced from it.