The volitional contribution is all-pervasive in our thinking.

Nothing is so pervasive as an atmospheric influence, and, in its way, nothing is so important.

Through the voices of the wind and the sea that we have learned to distinguish we catch another sound, curiously hollow and infinitely remote, not vaguely pervasive like the murmur of the sea, but round and precise like the beating of a drum somewhere on the confines of the earth.