127. I do not mean to say that the intellectual act does not refer to any object. I replace the idea by other acts of the soul, or by affections or representations of some kind or other, whether active or passive. This being so, if I am asked, for example, what is the immediate object of the intellectual act perceiving of determinate sensible intuition, I reply that it is the intuition itself. If the difficulty of explaining the union of such different things be urged, I answer: first, that this union exists in the unity of consciousness, as the internal sense attests: second, that the same difficulty militates against those who pretend that the understanding elaborates an intelligible species, which it takes from the sensible intuition; and how, I may ask, does the understanding place itself in contact with this intuition when it would elaborate its intelligible species. If this immediate contact be impossible in the one case, it will be equally so in the other; and if they concede it to be possible in their own case, they cannot deny it to be possible in ours also. When the understanding refers to no determinate intuition, but only to sensible intuitions in general, its immediate object is their possibility also in general, subject to the conditions of the object considered in general, and to those of every intelligence; among which, the principle of contradiction holds a primary place. CHAPTER XXI. DETERMINATE AND INDETERMINATE IDEAS. 128. We must, under pain of falling into sensism, by limiting the understanding to the perception and combination of objects presented by sensibility, admit other than intellectual acts referable to sensible objects in general. And what, in this case, is the object of the intellectual act, is a question as difficult as it is interesting. 129. The pure understanding can exercise its functions either upon determinate or indeterminate ideas; that is, upon ideas which contain something determinate, something realizable in a being, that is or may be offered to our perception, or upon ideas which represent general relations, without application to any object. Care should be taken not to confound general with indeterminate, or particular with determinate ideas. Every intermediate idea is a general idea, but not _vice versa_. The idea of _being_ is general and indeterminate; that of _intelligence_ is general but determinate. The particular idea refers to an individual; the determinate to a property, and it does not cease to be determinate although we abstract all relation in it to an existing individual. This distinction opens the way to considerations of the highest importance.