The division of causes in Aquinas’ De principiis naturae 5 establishes how the four classical Aristotelian causes may be divided. The text presents several difficulties, the most important of which are the number of divisions and the not-necessary contemporaneity of the being in potency of a cause and its effect. We aim to resolve these difficulties through a detailed analysis of the Latin text, resulting in a complete commentary on the chapter, which is a secondary contribution. Through this analysis, we resolve the main difficulties. First, by discovering a tacit distinction between the divisions of causes as considered in themselves and as known and verbalized by human beings, the number of the divisions is finally seven (four belonging to the being of causes and three to their knowledge). This distinction has a linguistic sign in the expressions ‘item’ and ‘sciendum est quod’. Secondly, the fact that it is not necessary for a cause and its caused to be simultaneously in potency, can be justified in the case of the singular predication if we consider that an architect, once the house is built, is still in potency of rebuilding that same house, if ever it lost the internal causes of its integrity.En este trabajo se ofrece un acercamiento explicativo al surgimiento del nominalismo medieval desde la perspectiva planteada por el historiador argentino José Luis Romero. Romero sugiere que existe una doble fuente, a saber, una histórica y otra filosófica. La primera de esas sería de orden empírico y correspondería a la burguesía y a su mentalidad. La segunda fuente, la académica, sería la que surge de la conocida querella de los universales durante los siglos XI y XII. Estas dos fuentes habrían sido la condición de posibilidad de posteriores desarrollos teóricos del nominalismo, los cuales suprimirán la idea de universal como algo real y sostendrán que lo único real son las cosas concretas, sensibles, mientras que los conceptos constituyen palabras vacías.