But without taking up more time on this discussion, it is sufficient to have shewn that the opinions we commonly have of the simple and complex are ideas of abstraction, that they cannot be applied to the compound productions of nature, and that when we attempt to reduce every being to elements of a regular figure, or to prismatic, cubical, or globular particles, we substitute our own imaginations in the place of realities; that the forms of the constituting particles of different bodies are absolutely unknown to us, and that, consequently, we can suppose, that an organized body is composed of organic particles, as well as that a cube is composed of other cubes. We have no other rule to judge by than experience. We perceive that a cube of sea-salt is composed of other cubes, and that an elm consists of other smaller elms, because, by taking an end of a branch, or root, or a piece of the wood separated from the trunk, or a seed, they will alike produce a new tree. It is the same with respect to polypuses, and some other kinds of animals, which we can multiply by cutting off, and separating any of the different parts;[BI] and since our rule for judging in both is the same, why should we judge differently of them? [BI] See Supplement to this Work, containing History of Birds, Fish, Insects, &c. vol. V. p. 377. It therefore appears very probable, by the above reasons, that there really exists in nature a number of small organized beings, alike, in every respect, to the large organized bodies seen in the world; that these small organized beings are composed of living organic particles, which are common to animals and vegetables, and are their primitive and incompatible particles, that the assemblage of these particles form an animal or plant, and consequently that reproduction, or generation, is only a change of form made by the addition of these resembling parts alone, and that death or dissolution is nothing more than a separation of the same particles. Of the truth of this we apprehend there will not remain a doubt, after reading the proofs we shall give in the following chapters. Besides, if we reflect on the manner in which trees grow, and consider how so considerable a volume can arise from so small an origin, we shall be convinced that it proceeds from the simple addition of small resembling organized particles. A grain produces a young tree, which it contained in miniature. At the summit of this small tree a bud is formed, which contains the young tree for the succeeding year, and this bud is an organic part, resembling the young tree of the first year's growth. A similar bud appears the second year, containing a tree for the third; and thus, successively, as long as the tree continues growing, at the extremity of each branch new buds will form, containing young trees like that of the first year. Thus it is evident, that trees are composed of small organized bodies, similar to themselves, and