Fundamental ideas of the cultural movement of Enlightenment were drawn up and encouraged in England by John Locke and introduced into continental Europe by Voltaire. The essence of this movement was defined by I. Kant in 1784. These new ideas were projected into the field of medicine initially with the systematization of anatomical studies by Winslow, Vicq d' Azyr and Sénac in France, by S. Th. Sömmerring and von Haller in Germany, and by Paolo Mascagni and other anatomists in Italy. This movement settled in Spain toward the middle of the XVIII century, due to Father Feijóo and his pupils such as Piquer and Casal. In New Spain, which maintained cultural and scientific relationship with the Old World, the leaders of the movement were José Antonio Alzate in the field of biology and José Ignacio Bartolache in that of medicine. These were the founders of the first scientific journals: the "Diario Literario" (Literary Journal) by Alzate (1768) and the "Mercurio Volante" (Flying Mercury) by Bartolache (1772). Latter this physician had to face the great epidemic outbreak of smallpox in 1779. Due to that, he attributed great importance to the psychological aspect of the problem and supported the variolization proceeding introduced into Mexico by Doctor Henri Morel. Moreover, two scientific expeditions, which reached New Spain at the end of the XVIII century, allowed to systematize the study of the American vegetables and to acknowledge the usefulness of botany and chemistry as auxiliary sciences of medicine.