In Plato's exposition of the Protagorean theory, the true doctrine held by Protagoras,[45] and the illusory explanation (whether belonging to him or to Plato himself), are singularly blended together. He denies expressly all separate existence either of Subject or Object--all possibility of conceiving or describing the one as a reality distinct from the other. He thus acknowledges consciousness and cognition as essentially bilateral. Nevertheless he also tries to explain the generation of these acts of consciousness, by the hypothesis of a _latens processus_ behind them and anterior to them--two continuous moving forces, agent and patient, originally distinct, conspiring as joint factors to a succession of compound results. But when we examine the language in which Plato describes these forces, we see that he conceives them only as Abstractions and Potentialities;[46] though he ascribes to them a metaphorical copulation and generation. "Every thing is motion (or change): of which there are two sorts, each infinitely manifold: one, having power to act--the other having power to suffer." Here instead of a number of distinct facts of consciousness, each bilateral--we find ourselves translated by abstraction into a general potentiality of consciousness, also essentially bilateral and multiple. But we ought to recollect, that the Potential is only a concept abstracted from the actual,--and differing from it in this respect, that it includes what has been and what may be, as well as what is. But it is nothing new and distinct by itself: it cannot be produced as a substantive antecedent to the actual, and as if it afforded explanation thereof. The general proposition about motion or change (above cited in the words of Plato), as far as it purports to get behind the fact of consciousness and to assign its cause or antecedent--is illusory. But if considered as a general expression for that fact itself, in the most comprehensive terms--indicating the continuous thread of separate, ever-changing acts of consciousness, each essentially bilateral, or subjective as well as objective--in this point of view the proposition is just and defensible.[47] [Footnote 45: The elaborate Dissertation of Sir William Hamilton, on the Philosophy of the Unconditioned (standing first in his 'Discussions on Philosophy'), is a valuable contribution to metaphysical philosophy. He affirms and shows, "That the Unconditioned is incognisable and inconceivable: its notion being only a negation of the Conditioned, which last can alone be positively known and conceived" (p. 12); refuting the opposite doctrine as proclaimed, with different modifications, both by Schelling and Cousin.