In the time of Plato, distinction between the two classes of words, Concrete and Abstract, had not become so clearly matter of reflection as to be noted by two appropriate terms: in fact, logical terminology was yet in its first rudiments. It is therefore the less matter of wonder that Plato should not here advert to the relation between the two, or to the different sense in which existence might properly be predicable of both. He agrees with the materialists or friends of the Concrete, in affirming that sensible objects, Man, Horse, Tree, exist (which the Idealists or friends of the Abstract denied): but he differs from them by saying that other Objects, super-sensible and merely intelligible, exist also--namely, Justice, Virtue, Whiteness, Hardness, and other Forms or Attributes. He admits that these last-mentioned objects do not make themselves manifest to the senses; but they do make themselves manifest to the intelligence or the conception: and that is sufficient, in his opinion, to authenticate them as existent. The word _existent_, according to his definition (as given in this dialogue), includes not only all that is or may be perceived, but also all that is or may be known by the mind; _i.e._, understood, conceived, imagined, talked or reasoned about. Existent, or Ens, is thus made purely relative: having its root in a Subject, but ramifying by its branches in every direction. It bears the widest possible sense, co-extensive with _Object_ universally, either of perception or conception. It includes all fictions, as well as all (commonly called) realities. The conceivable and the existent become equivalent. [Side-note: Narrower meaning given by Materialists to Ens--they included only Objects of Perception. Their reasoning as opposed to Plato.]