Physical sensation even came from will.

So he would imagine that he heard spirits in the air all about him, not anything weird or hostile, but just kindly people of the clouds and winds, such as those created by the old Greeks.
Fancying that he heard whispers about him and resolved to hear them, he heard them.

If a powerful imagination wanted to create whispers it could create them.

The spirits of the air, Tayoga's spirits, the spirits of old Hellas, were singing in either ear, and the song, like that of the sea, like the flavor breathed out by his Christmas celebration, was full of courage, alive with hope.
He had kept his eyes closed a full half hour, because, with sight shut off, the other senses became much more acute for the time.

The power that had been in the eyes was poured into their allies.