A memory is whatever you think happened sometime in the past.
Imagination is whatever you think might happen sometime in the future.
A dream is whatever you think is happening while your body sleeps.
Perception is whatever you think your world consists of at any given moment.
Thought is the invisible, creative power that gives shape, form and feeling to the life force energy as it flows through every living being.
We cannot see thought, just as we cannot see gravity.
What we can notice are the effects of thought (and of gravity) and adjust our relationship to it accordingly, thereby saving ourselves an immense amount of trouble!