It is impossible for one moment to affirm that our knowledge is so complete, that we have a scientific acquaintance with the causes of all our varied mental phenomena, and the laws which regulate them. We have ascertained the nature of several of our mental processes; but how small a portion of man’s mental activity do they embrace. I need only particularize a few of which we are in complete ignorance, as to the forces which generate them, and the laws which regulate their action. First, with respect to Genius. Genius is a mental power which manifests itself only on rare occasions. Who can affirm that we have ascertained the law which regulates its birth? We may judge from analogy that this, as other things, follows a law of some kind; but respecting the causes which give it birth our philosophy is profoundly ignorant. Nor have we any knowledge of its mode of action. It manifests itself in various forms. There is the genius which makes the poet, the philosopher, the scientific discoverer, the orator, the politician, and many others. How those who are possessed of this power effectuate their mental operations, or how their great ideas originate in their minds is a subject which exceeds the limits of our scientific knowledge. Take for example the genius of the poet. Whence came, and what was the nature of that intuitive power with which Shakespeare was endowed, or how was it called into exercise? We call such powers intuitions. We say that a great poet is endowed with a species of inspiration. What is this but to confess our entire ignorance both of the origin and the mode of his mental operations. Probably the poet himself would be unable to give us any analysis of the origin of his own thoughts, or of the laws that regulate them. How then can we venture to affirm that they must all originate in the mind itself, and not be due to the action of some external power? The habit of speaking of his inspirations, from which scientific men are not exempt, proves our complete ignorance both of its nature and origin.