Sometimes he reveals the mind of a seer or poet, throwing out conclusions which are highly suggestive, on the face of them convincing, but which on examination prove untenable, or at best must be set down as unproven or needing qualification.

But these were just the slag from the great furnace of his mind, slag not always worthless.

Brilliant and far-reaching as were his conclusions, he did not execute a well-ordered plan.

Rather he grew with his work, and his work and its problems grew with him.

He took a mountain-top view of things, kept his eyes always on the far horizon, and in the splendid sweep of his scientific conceptions sometimes overlooked the details near at hand.