But what as to mind? To find what shall be called mind, let us suppose an individualized object which is not an isolated object, or a universe to itself, but a member in a system; then, in obedience to what has been stated, that object must be at once self-manifesting and impressed by the other objects around it, and, in being so impressed, assimilated to them more or less.... Admitting the self-manifesting power to be sensitive, percipient, or conscious, then quantity or intensity of substance or power in a monad is the condition requisite for feeling and thought. And thus, by an immediate co-ordination of our fundamental ideas of self-manifesting power and assimilative action, more or less, we reach a distinct conception of mind viewed in relation with that which is not mind. By this deduction, the primeval created substance, the true protoplasm is still supposed to be homogeneous, animated by its assimilation to the everlasting, the Infinite.
This protoplasm is partitioned in varying degrees so that there are in creation some individualized or separate objects or forces consisting of so small an amount or such weakness of substance that they are wholly fixed and merely perceptible, while there are others consisting of so much more that they are free in their inner life, and have power to perceive themselves also--not, indeed, in the centres of their being, and as unimpressed and without ideas, but as members in a system, impressed or assimilated by other objects, and so having ideas, with power to look in this direction or that, and to act accordingly.
Such, then, according to Macvicar, is the nature of mind or spirit. It is a being so constituted as to be at once in possession of ideas, and so far fixed; and also in possession of undetermined life or activity, and so far free. These are, as it were, the opposite poles of its being, and the conditions of its activity. If either is wanting, the other vanishes. Without something fixed in the mind, some object of thought or feeling, there can be no thinking or feeling. Without something unfixed there can be nothing to think or to feel with, much less can there be any thinking or feeling of self--that is, self-consciousness. But, grant this condition in the individual, and add the law of assimilation, operating first from God above, thus giving reason and conscience, on the higher aspect of our being; and, secondly, from nature around, thus giving observation and instincts harmonious with our situation in the system of the universe, and then human nature emerges.