The world of our experience consists at all times of two parts, an objective and a subjective part, of which the former may be incalculably more extensive than the latter, and yet the latter can never be omitted or suppressed. The objective part is the sum total of whatsoever at any given time we may be thinking of, the subjective part is the inner "state" in which the thinking comes to pass.

Lecture XX, "Conclusions" - The Varieties of Religious Experience (1902)