Once liberal arts were rejected and modern studies focused in arithmetics and geometry, Descartes dedicated his work to the production of truth science and not to the education of public men. Its in this area where he ll be criticised by Elizabeth the bohemian princess and Giambattista Vico. On the one hand, the boehmian princess writes to the french philosopher asking him about the unity between the soul and the body, which is a fundamental problem in Meditationes de Prima Philosophia. Is in this letters between Isabel and Descartes where we find the elements necesary for establishing a new way of comprehending Descartes philosophy, a philosophy that goes beyond the problem of the truth. This is the starting point for a moral thought that takes into account the region of the world where everything is clear and confusing. This is the region of human affairs. On the other hand, the italian philosopher developes from his epistemological principle the verum factum (we can only know what we create)an epistemology of blacks and whites in which we can draw what s human. In this region the geometrical truth its not important, whats really important is the cience of prudency.