For one person who can think, there are at least a hundred who can observe. An accurate observer is, no doubt, rare; but an accurate thinker is far rarer.
In every great epoch there is some one idea at work which is more powerful than any other, and which shapes the events of the time and determines their ultimate issues.
Knowledge is not an inert and passive principle, which comes to us whether we will or no; but it must be sought before it can be won; it is the product of great labour, and therefore of great sacrifice.
Practice aims at what is immediate; speculation at what is remote. In practical life, the wisest and soundest men avoid speculation, and ensure success, because, by limiting their range, they increase the tenacity with which they grasp events, while in speculative life the course is exactly the reverse, since in that department the greater the range the greater the command.
The faculty of art is to change events; the faculty of science is to foresee them. The phenomena with which we deal are controlled by art; they are predicted by science.