accordingly a mere accident, and passes away as all accidents do; its existence is due chiefly to matter, by the varying "dispositions" of which the universal form is "determined" to this or that particular form; matter is in general the source of all particularity, all number and measure. The difficulty underlying this attribution of diversity to a matter which is supposed to be, apart from the _form_, undetermined and undifferentiated, has been referred to above. It is emphasised in the argument to this part of the _Causa_ given in the introductory epistle,[267] where matter, although formless in itself, is spoken of as "consisting in diverse grades of active and passive qualities?" Bruno seems, however, at this time unconscious of the difficulty. Certainly from pure matter and pure form, body and spirit, standing over against one another, no start could be made. Diversity had to come into the world somehow. [Sidenote: The deduction of matter.] We have not yet solved the problem as to the relation between these two principles themselves--matter and form. Bruno confesses to have held at one period the "Epicurean view that matter was the only substance, the forms being merely accidental dispositions of it; but on further consideration he was compelled to recognise a formal as well as a material substance."[268] In fact, however, both form and matter tend as the philosophy develops to coincide in a higher unity which is at last the ultimate reality. The "proof" of "Matter" is from the analogy between Nature and Art. All who have attempted, said Bruno, to distinguish _matter_ from _form_ have made use of the analogy of the arts (_e.g._ the Pythagoreans, Platonists, Peripatetics). Take some art such as that of the wood-worker; in all its forms and all its operations it has as subject (or material) wood--as the iron-worker has iron; the tailor, cloth. All these arts produce each in its own material various pictures, arrangements, figures, none of which is proper or natural to that material. So Nature, which art resembles, must have for its operations a certain matter (material); for no agent intending to make something can work without something _of_ which to make it, or wishing to act can do so without something _on_ which to act; there is therefore a species of subject or material, of which and in which _nature_ effectuates its operation, its work, and which is by it formed in the many forms presented to the eye of reflection. And as wood by itself has not any artificial form, but may have any or all through the action of the wood-worker, so the matter of which we speak, of itself and in its own nature, has not any _natural_ form, but may have any or all through the agent, the active principle of nature. This natural matter or material is imperceptible, differing so from the material of art, because the matter of nature has absolutely no form, whereas the matter of art is a thing already formed by nature.