Four years after the death of Justinian, A.D. 569, was born at Mecca, in Arabia the man who, of all men exercised the greatest influence upon the human race . . . Mohammed . . .

The history of Science is not a mere record of isolated discoveries; it is a narrative of the conflict of two contending powers, the expansive force of the human intellect on one side, and the compression arising from traditionary faith and human interests on the other.

Experimental investigation, to borrow a phrase employed by Kepler respecting the testing of hypotheses, is "a very great thief of time." Sometimes it costs many days to determine a fact that can be stated in a line.

Over events, we may have some control, but over the law of life's progress none.

So great was the preference given to sacred over profane learning that Christianity had been in existence fifteen hundred years, and had not produced a single astronomer.

Time, to the nation as to the individual, is nothing absolute; its duration depends on the rate of thought and feeling.

Is it not true that for every person the course of life is along the line of least resistance, and that in this the movement of humanity is like the movement of material bodies?