Aaron Hills was president of Texas Holiness University. Hills was so heavily influenced by Charles G. Finney that he wrote a book about Finney's life. Hills was part of the Holiness movement, which emphasized that the process of salvation involves two crises. In the first, conversion or justification, one is freed from the sins he has committed. In the second, entire sanctification or full salvation, one is liberated from the flaw in his moral nature that causes him to sin.