As a Man Thinketh centers on the idea that positive thinking leads to positive consequences in life. Allen explores various facets of this idea, arriving at the understanding that thought directly shapes people’s characters and the outcomes of their lives. In the opening lines of the text, he states, “A man is literally what he thinks, his character being the complete sum of all his thoughts” (7). Allen uses gendered language throughout the text, consistent with other writings from the early 20th century, but the term “man” applies to any person. The idea that people shape themselves and their lives according to their thoughts is consistent with New Thought philosophies.

Allen frequently pushes back against the idea that chance or luck are significant, asserting that the quality of each person’s selfhood stems almost exclusively from the quality of their thoughts:

A noble and Godlike character is not a thing of favour or chance, but is the natural result of continued effort in right thinking, the effect of long-cherished association with Godlike thoughts. An ignoble and bestial character […] is the result of the continued harbouring of grovelling thoughts (8).

Allen highlights the importance of “continued” efforts to promote positive thinking by repeating the term twice, using