De Magnetica [...] Plantarum p. 613

survival: the first is that the parts be correctly attached to each other, and that the individual limbs of the body be arranged in order, namely that the head should be supported by the neck, the neck by the chest, the chest by the legs, like columns sustaining the mass of the whole edifice. The second is that the whole assemblage of such an edifice should stand erect, built in an orderly relationship to the universe, with the head pointing up and the feet down; if this were done differently, and the body were inverted, or inclined outside the directional line, it would necessarily suffer the greatest violence as a result of this position most contrary to its nature. All of which applies to all of the many things that have been produced. Accordingly, as profusely explained in the preceding pages, the elements so studiously observe the arrangement of their position that it is easier for the world to slip than for them undergo the violence of a contrary position. Hence fire and air, if enclosed in the earth, break, split and scatter everything so they may enjoy the free range of their own domain. Hence, since the heavy cannot coexist with the light, floods, ruination, and the burying of cities and whole provinces, must inevitably be caused by the impulse of weight tending to its natural place and centre. Thus individual minerals keep to their particular and appropriate seats on earth, so that if removed from them they immediately perish; hence some prefer their individual lodgings dry, some damp, some hot, and the rest cold; hence lead, subjected to constant salt water, is dissolved into quicksilver; iron mines too, under the tyranny of water, disappear into red liquid; but to return to where we began, this natural appetite is moreover seen very much both in lodestone and in plants and fruits; so, just as lodestone has two ends, North and South, it seems necessary to its survival that the parts, or fibres tending towards it ends should not only be well arranged in respect to each other and hold their due position along the length, but also that they should have a suitable position with respect to the universe, for otherwise they cannot comfortably preserve themselves; and thus a plant too requires not only that the trunk be placed over the roots, and upright, so it can luxuriate in branches and side-shoots, but also, to preserve its vigour, it is necessary that the root be buried in the ground and the stem turn upward. But just as the force of lodestone is propagated lengthwise by certain fibres, so vegetal things also have certain fibres, or pores, through which they may communicate to their individual parts the nutriment they have consumed.