"As a Man Thinketh" is a great philosophical piece written in 1903 by James Allen, a pioneer of the self-help movement.

"As a Man Thinketh" is an essay and self-help classic, which argues that the key to mastering your life is harnessing the power of your thoughts and helps you cultivate the philosophy and attitude of a positive, successful person.

In its theme that 'mind is the master weaver', creating our inner character and outer circumstances, "As a Man Thinketh" is an in-depth exploration of the central idea of self-empowerment writing.
James Allen's contribution was to take an assumption we all share - that because we are not robots we therefore control our thoughts - and reveal its fallacy. Because most of us believe that mind is separate from matter, we think that thoughts can be hidden and made powerless - this allows us to think one way and act another. But Allen believed that the unconscious mind generates as much action as the conscious mind, and while we may be able to sustain the illusion of control through the conscious mind alone, in actuality we are continually faced with a question, 'Why cannot I make myself do this or achieve that?' In noting that desire and will are sabotaged by the presence of thoughts that do not accord with the desire, Allen was led to the startling conclusion that, 'We do not attract what we want, but what we are.' Achievement happens because you as a person embody the external achievement; you don't 'get' success but become it. There is no gap between mind and matter.