But is the abstract essence itself—apart from all mental analysis of it, apart from all comparison of it with its constituent factors or with other essences—in any sense _necessary_? There is no question of its actual existence, but only of itself as an object of thought. Now our thought does not seem to demand _necessarily_, or have a _necessary_ connexion with, any particular object of which we do _de facto_ think. What we do think of is determined by our experience of _actual_ things. And the things which we conceive to be possible, by the exercise of our reason upon the data of our senses, memory and imagination, are determined as to their nature and number by our experience of actual things, even although they themselves can and do pass beyond the domain of actually experienced things. The only necessary object of thought is reality in general: for the exercise of the function of thought necessarily demands an object, and this object must be reality of some sort. Thought, as we saw, begins with actual reality. Working upon this, thought apprehends in it the foundations of those necessary relations and judgments already referred to. Considering, moreover, the actual data of experience, our thought can infer from these the actual existence of one Being Who must exist by a necessity of His Essence. But, furthermore, must all the possible essences which the mind does or can actually think of, be conceived as _necessarily possible_ in the same sense in which it is suggested that they must be conceived as eternally possible? To this question, too, we shall return presently. (_d_) Finally, possible essences appear to the mind as _immutable_, and consequently _indivisible_. This means simply that the relations which we establish between them and their constitutive factors are not only necessary but immutable: that if any constitutive factor of an essence is conceived as removed from it, or any new factor as added, we have no longer the original essence but some other essence. If “animal” is a being essentially embodying the two objective concepts of “organism” and “sentient,” then on removing either we have no longer the essence “animal”. So, too, by adding to these some other element compatible with them, _e.g._ “rational,” we have no longer the essence “animal,” but the essence “man”. Hence possible essences have been likened to numbers, inasmuch as if we add anything to, or subtract anything from, any given number, we have now no longer the original number but another.(90) This, too, is only an expression of the laws of identity and contradiction. We might ask, however, whether, apart from analysis and comparison of an abstract object of thought with its constitutive notes or factors, such a possible essence is in itself _immutably_ possible. This is similar to the question whether we can or must conceive such a possible essence as eternally and necessarily possible.