In general, all the objective ratios which immediately follow the constitution of a concrete being need no additional principles, because they are already contained in the entity of the concrete being, in which the intellect finds its ground for their distinct conception. And here let us add two remarks. The first is that all such intelligible ratios identify themselves really, though inadequately, with the concrete entity of which they are predicated; so that between the attribute and its concrete subject there can be but the slightest of metaphysical distinctions. The second is that the essential attributes of a _simple_ being are never _really_ distinct from one another. The reason of this is evident; for such attributes are the simple actuality of a simple being, which does not cease to be identical with itself when it is viewed from different points of view. They admit, however, of a distinction of reason; for when the same thing is considered under different aspects, the distinct concepts that are then formed by the mind evidently exhibit distinct objective ratios, every one of which corresponds to one of those aspects without formally implying the others. Though we have hitherto spoken of the essential attributes and properties of _primitive_ beings, the doctrine we have expounded is also applicable to those of all substantial compounds. Thus the attributes and properties of a molecule of hydrogen, oxygen, or any other specific compound have the reason of their being in the essential principles of their respective compound, and nothing else is required to account for them, as is evident from the preceding explanations. It is to be observed, however, that in such compounds as owe their being to material composition only, as it is the case with all the molecules of natural bodies, the composition which is the essential form of the compound is not a substantial, but an accidental, determination of the components; and hence it is that each such molecule involves in its essential constitution _both substance and accident_, and therefore is not exactly a substance, but a natural compound essence. The consequence is that its essential attributes, too, owe their being not only to the component substances, but also to such accidents as are essentially implied in the constitution of the compound. Thus, _porosity_, _compressibility_, _bulk_, etc., which are essential attributes of each molecule as such, have the reason of their being partly in the elements of which they are made up, and partly in the specific form of their composition. Now, this specific form may undergo accidental changes _without trespassing the bounds of its species_; and those essential attributes which depend on the specific composition may consequently undergo a change in their degree; and since none of those changeable degrees are determinately required by the essence of the molecular compound, it follows that the essential attributes and