As to number, ideas are limited only by the number of kinds, without direct relation to degrees; every object, therefore, having in itself a _distinctive essential_, has also its distinct idea; while two or more objects of the same kind, however differing in degree, must consequently refer only to one and the same. For instance, though a hundred animals should differ in size, strength, or color, yet, if none of these peculiarities are essential to the species, they would all refer to the same supreme idea.
The same law applies equally, and with the same limitation, to the essential differences in the intellectual, the moral, and the spiritual. All ideas, however, have but a potential existence until they are called into the consciousness by some real object; the required condition of the object being a predetermined correspondence, or correlation. Every such object we term an _assimilant_.
With respect to those ideas which relate to the physical world, we remark, that, though the assimilants required are supplied by the senses, the senses have in themselves no _productive, coöperating_ energy, being but the passive instruments, or medium, through which they are conveyed. That the senses, in this relation, are merely passive, admits of no question, from the obvious difference between the idea and the objects. The senses can do no more than transmit the external in its actual forms, leaving the images in the mind exactly as they found them; whereas the intuitive power rejects, or assimilates, indefinitely, until they are resolved into the proper perfect form. Now the power which prescribes that form must, of necessity, be antecedent to the presentation of the objects which it thus assimilates, as it could not else give consistence and unity to what was before separate or fragmentary. And every one who has ever realized an idea of the class in which alone we compare the assimilants with the ideal form, be he poet, painter, or philosopher, well knows the wide difference between the materials and their result. When an idea is thus realized and made objective, it affirms its own truth, nor can any process of the understanding shake its foundation; nay, it is to the mind an essential, imperative truth, then emerging, as it were, from the dark potential into the light of reality.