The metaphysical principles of the infinitesimal calculus

"PROCEEDING IN A MANNER INVERSE to that of profane science, and in accordance with the unchanging perspective of all traditional science, we must before all else set forth the principle that will allow us almost immediately to resolve the difficulties to which the infinitesimal method has given rise, without letting ourselves be led astray by potentially interminable discussions, as indeed happens in the case of those modern philosophers and mathematicians who, by the very fact that they lack this principle, have never provided a satisfactory and definitive solution to these difficulties."