Theologians maintain that just the presence of a feeling of God inMan's heart, is, in itself, a proof of His existence. Since &ndash,asthey assure us- that feeling is innate, it&rsquo,s actually areminiscence. Well, if it&rsquo,s as they say, Blanca, then, alongwith a feeling of God (and, as I hope to demonstrate during the course of these letters, closely bound to it), there exists in Man's heartanother innate feeling of no less power. The feeling of the twin soul, of the one creature who, out of every other, is destined to us, forit&rsquo,s the other half that will us complete us." Thus begins oneof the letters of this epistolary essay in which the author undertakes an exhaustive tracing of the theory of soul mates in the history ofReligion and Philosophy, of Literature and Occult Sciences, showingthe preeminent place that in the worldview of the ancient sagesoccupied this enigmatic feeling that we know today with the name ofromantic love.