It is necessary further to assume the existence of other properties in the atoms, in order to account for the variety in Nature, and the individuality of existing things. They have original differences in form; some are smooth, others round, others rough, others hooked, &c. These varieties in form are not infinite, but limited in number.
As the diversity in the world depends on the diversity of these forms, the order and regularity of Nature imply that there is a limit to these varieties. But while they are limited, the individuals of each kind are infinite, otherwise the primordial atoms would be finite in number, and there could be no cohesion among atoms of the same kind, in the vast and chaotic sea of matter—
Unde ubi qua vi et quo pacto congressa coibunt
Materiae tanto in pelago turbaque aliena[7]?
The motions which tend to the support and the destruction of created things are balanced by one another: there must be an equilibrium in these opposing forces—
Sic aequo geritur certamine principiorum
Ex infinito contractum tempore bellum[8].
Death and birth succeed one another, as now the vitalising, now the destructive forces gain the upper hand.
Further, the great diversity in Nature is to be accounted for by diversity, not only in the original forms of matter, but also in their modes of combination. No existing thing is composed solely of one kind of atoms. The greater the variety of forces and powers which anything displays, the greater is the variety of the elements out of which it was originally composed. Of all visible objects the earth contains the greatest number of elements; therefore it has justly obtained the name of the universal mother. There is however a limit to the modes in which atoms can combine with one another: each nature appropriates elements suitable to its being and rejects those unsuitable. All existing things differ from one another in consequence of the difference in their elements and in their modes of combination. The different modes of combination give rise to many of the secondary properties of matter, which are not in the original elements. Colour, for instance, is not one of the original properties of atoms: for all colour is changeable, and all change implies the death of what previously existed. Moreover, colour depends on light, and the atoms never come forth into the light. The atoms are also devoid of heat and cold, of sound, taste, and smell. All these properties must be kept distinct from the original elements—
Immortalia si volumus subiungere rebus