Conclusion.
I will now conclude, as I began, by invoking the attention of my reader to a subject which, if he is young, may be of importance to him in after-life. He may reasonably ask what peculiarities of mind enabled me to accomplish what even the most instructed in their own sciences deemed impossible.
I have always carefully watched the exercise of my own faculties, and I have also endeavoured to collect from the light reflected by other minds some explanation of the question.
I think one of the most important guiding principles has been this:—that every moment of my waking hours has always been occupied by some train of inquiry. In far the largest number of instances the subject might be simple or even trivial, but still work of inquiry, of some kind or other, was always going on.
The difficulty consisted in adapting the work to the state of the body. The necessary training was difficult. Whenever at night I found myself sleepless, and wished to sleep, I took a subject for examination that required little mental effort, and which also had little influence on worldly affairs by its success or failure.
On the other hand, when I wanted to concentrate my whole mind upon an important subject, I studied during the day all the minor accessories, and after two o'clock in the morning I found that repose which the nuisances of the London streets only allow from that hour until six in the morning.
At first I had many a sleepless night before I could thus train myself.
I believe my early perception of the immense power of signs in aiding the reasoning faculty contributed much to
