In Montaigne, the self is the product of plurality and it does not exist separated from nature. On the contrary in Descartes, the “voice of reason” justifies a lonesomeness which renounces to the body, the senses and the voices of others. According to Montaigne, knowledge is sought in permanent relationship with the world, without the expectation of an absolut certainty that would exceed our natural smallness. According to Descartes, the individual research is safer than one in which several individuals intervene. However, the difference between both thinkers is not delimited for the plane of knowledge only. Actually, it has biographical roots and, above all, responds to two profoundly opposed views of the human condition.