Descartes is often considered the prototype of the dualistic philosopher, i.e. his philosophy admitted the coexistence of two irreducible principles. However, in his last published book of his living The Passions of the Soul, also known as the Treatise on the Passions, Descartes deliberately adopts a materialistic stance and studies the passions as a physician, thus breaking with the tradition of scholasticism. Christian ideology had a mystical conception of the emotions based on love, the first of the passions. For Descartes, the movements of the soul (understood as an animated body) are divided into voluntary movements (actions) and involuntary movements (passions). Both actions and passions are movements of the body and lend themselves to a materialistic evaluation. Emotions are then bodily movements. According to Descartes, the first of the passions, which conditions all the other passions, is admiration. The term 'admiration' in seventeenth-century French expresses the fact of having one's gaze drawn to a new event that attracts one's attention. Admiration is a cognitive emotion in this sense that tells us about the incursion of the new into our lives. In this paper, I will present The Treatise on the Passions as a dynamic part of the process of the laicization of thought at work in modern philosophy.