Abel Sanchez has been called Unamuno’s first mature and fully realized novel. It is certainly his first starkly symbolic novel, for it is bare of any social or otherwise realistic context; the characters are allowed to stand alone on a stage of purely representative relationships. As such, the work falls into the tradition of the parable. Although the character of Joaquin seems to be thoroughly explored, he is the existential state of hatred brought mythically into the world by his namesake, the biblical Cain.
This short novel, like the other fictional works of Unamuno, is governed by the philosophical ideas which infuse it. The author, often called an early existentialist thinker, is here primarily interested in exploring, as he does in his other fictions, the implications of hatred as a basic human state which alienates the self and creates its own identity. Thus, Abel Sanchez is a thesis novel of some philosophical complexity, created in the period of time between the great poetic parables of the isolated man of the Romantic movement and the fictional depictions of the existential hero of the modern period.