S. Austin Allibone, comp. Prose Quotations from Socrates to Macaulay. 1880.
Our minds are so constructed that we can keep the attention fixed on a particular object until we have, as it were, looked all around it; and the mind that possesses this faculty in the highest degree of perfection will take cognizance of relations of which another mind has no perception. It is this, much more than any difference in the abstract power of reasoning, which constitutes the vast difference between the minds of different individuals. This is the history alike of the poetic genius and of the genius of discovery in science. I keep the subject, said Sir Isaac Newton, constantly before me, and wait until the dawnings open by little and little into a full light. It was thus that after long meditation he was led to the invention of fluxions, and to the anticipation of the modern discovery of the combustibility of the diamond. It was thus that Harvey discovered the circulation of the blood, and that those views were suggested by Davy which laid the foundation of that grand series of experimental researches which terminated in the decomposition of the earths and alkalies.
In the power of fixing the attention, the most precious of the intellectual habits, mankind differ greatly; but every man possesses some, and it will increase the more it is exerted. He who exercises no discipline over himself in this respect acquires such a volatility of mind, such a vagrancy of imagination, as dooms him to be the sport of every mental vanity: it is impossible such a man should attain to true wisdom. If we cultivate, on the contrary, a habit of attention, it will become natural; thought will strike its roots deep, and we shall, by degrees, experience no difficulty in following the track of the longest connected discourse.
He will have no more clear ideas of all the operations of his mind, than he will have all the particular ideas of any landscape or clock, who will not turn his eyes to it and with attention heed all the parts of it.