The Eleate now turns to the philosophers of the opposite school--the Mentalists or Idealists,--whom he terms the friends of Forms, Ideas, or species.[51] These men (he says) distinguish the generated, transitory and changeable--from Ens or the Real, which is eternal, unchanged, always the same: they distinguish generation from essence. With the generated (according to their doctrine) we hold communion through our bodies and our bodily perceptions: with Ens, we hold communion through our mind and our intellectual apprehension. But what do they mean (continues the Eleate) by this "holding of communion"? Is it not an action or a passion produced by a certain power of agent and patient coming into co-operation with each other? and is not this the definition which we just now laid down, of Ens or the Real. [Footnote 51: Plato, Sophist. p. 248 A. [Greek: tou\s tô=n ei)dô=n phi/lous].] [Side-note: Holding communion--What? Implies Relativity. Ens is known by the mind. It therefore suffers or undergoes change. Ens includes both the unchangeable and the changeable.] _No_--these philosophers will reply--we do not admit your definition as a definition of Ens: it applies only to the generated. Generation does involve, or emanate from, a reciprocity of agent and patient: but neither power nor action, nor suffering, have any application to Ens or the Real. But you admit (says the Eleate) that the mind knows Ens:--and that Ens is known by the mind. Now this _knowing_, is it not an action--and is not the _being known_, a passion? If _to know_ is an action, then Ens, being known, is acted upon, suffers something, or undergoes some change,--which would be impossible if we assume Ens to be eternally unchanged. These philosophers might reply, that they do not admit _to know_ as an action, nor _to be known_ as a passion. They affirm Ens to be eternally unchanged, and they hold to their other affirmation that Ens is known by the mind. But (urges the Eleate) can they really believe that Ens is eternally the same and unchanged,--that it has neither life, nor mind, nor intelligence, nor change, nor movement? This is incredible. They must concede that Change, and the Changeable, are to be reckoned as Entia or Realities: for if these be not so reckoned, and if all Entia are unchangeable, no Ens can be an object of knowledge to any mind. But though the changeable belongs to Ens, we must not affirm that _all_ Ens is changeable. There cannot be either intellect or knowledge, without something constant and unchangeable. It is equally necessary to recognise something as constant and unchangeable--something else as moving and changeable: Ens or reality includes alike one and the other. The true philosopher therefore cannot agree with those "Friends of Forms" who affirm all Ens or Reality to be at rest and unchangeable, either under one form or under many:--still less can he agree with those opposite reasoners, who maintain all reality to be in perpetual change and movement.