Not only is it the sole way we have of knowing mind; without it there would be no mind to know.

Not to be conscious of one's self is, mentally speaking, not to be.

This complex entity, this little cosmos of a world, the "I," has for its very law of existence self-consciousness, while personality is the effect it produces upon the consciousness of others.
But we may push our inquiry a step further, and find in imagination the cause of this strange force.

For imagination, or the image-making faculty, may in a certain sense be said to be the creator of the world within.

The separate senses furnish it with material, but to it alone is due the building of our castles, on premises of fact or in the air.