He dwelt on the paramount importance of beginning from the very bottom of the scale of fact, of understanding the commonplace things at our feet, so full of wonder and mystery and instruction, before venturing on theories.

The sun is not polluted by shining on a dunghill, and no facts were too ignoble to be beneath the notice of the true student of nature.

But his own genius was for the grandeur and pomp of general views.

The practical details of experimental science were, except in partial instances, yet a great way off; and what there was, he either did not care about or really understand, and had no aptitude for handling.

He knew enough to give reality to his argument; he knew, and insisted on it, that the labour of observation and experiment would have to be very heavy and quite indispensable.