New Thought Movement · 1903 to Present · As a Man Thinketh in His Heart
A man is literally what he thinks, his character being the complete sum of all his thoughts.James Allen — As a Man Thinketh, 1903
The self-concept is the totality of beliefs a person holds about who they are — their abilities, their worth, their identity, their possibilities. It operates as a filter through which all experience is interpreted and as a set of invisible constraints on what a person believes they can achieve. The person who believes they are "not a math person" will not persist through difficulty in learning mathematics. The person who believes they are fundamentally unlovable will interpret ambiguous social signals as confirmation. The self-concept is not destiny, but it functions like one until it is examined and revised.
James Allen's insight in As a Man Thinketh — that what a person believes about themselves, at the level of felt conviction rather than surface affirmation, determines the quality of their actions — was ahead of its time. Contemporary psychology has confirmed and elaborated this in multiple frameworks: self-efficacy theory (Bandura), self-determination theory (Deci and Ryan), and the extensive literature on implicit self-theory (Dweck's growth versus fixed mindset distinction). All of these share the core observation that beliefs about the self function as operating assumptions that shape behavior far below the level of conscious deliberation.
This makes the self-concept both the most important and the most difficult target for deliberate change. It cannot be revised through surface-level affirmation alone — the subconscious mind, as Hill observed, is not fooled by declarations it doesn't feel are true. It requires the slower, more effortful work of accumulated evidence: acting in the direction of a desired identity, noticing the results, and gradually revising the stored image in light of actual experience.
The philosophical lineage of the self-concept runs from Socrates' "know thyself" through Descartes' cogito to William James's foundational psychology of the self. James distinguished between the "I" — the self as knower — and the "Me" — the self as known, the accumulated image of oneself built from experience and reflection. It is the "Me" that corresponds to the self-concept: the stable, organized set of beliefs about oneself that functions as the psychological ground from which all action proceeds.
Alfred Adler, whose work influenced Hill's thinking through Andrew Carnegie and others, developed the concept of the "life style" — the unique pattern of goals, beliefs, and interpretations through which each person engages with the world, formed in early childhood and largely unconscious thereafter. For Adler, psychological health required bringing this operating style into conscious awareness and revising the mistaken beliefs embedded in it. This is essentially the same program that contemporary cognitive therapy pursues.
The New Thought tradition, which produced Allen's book, took a characteristically practical stance: if the self-concept determines behavior, and behavior determines outcomes, then the most efficient point of intervention is the self-concept itself. The earnest daily repetition of affirmations — whatever one thinks of the metaphysics — is an attempt to revise the self-concept by flooding it with new input. The practice works better than critics suggest and less well than promoters claim, but the underlying insight about the primacy of self-belief is sound.
Whether you think you can, or you think you can't — you're right.Henry Ford — as attributed