A font is a source, or basis, or cause for the morality of an act. An act is immoral if any one or more of these fonts is bad. An act is moral only if all of the fonts of morality are good. There are three fonts of morality.
FIRST FONT: The intended end (or purpose) for which the act is chosen.
SECOND FONT: The inherent ordering of the act itself toward its moral object. This ordering constitutes the moral species, i.e. the essential moral nature, of the chosen act.
THIRD FONT: The circumstances pertaining to the morality of the act, especially the consequences.
Catechism of the Catholic Church: “The morality of human acts depends on: the object chosen; the end in view or the intention; the circumstances of the action. The object, the intention, and the circumstances make up the ‘sources,’ or constitutive elements, of the morality of human acts.”
Compendium of the Catechism: “The morality of human acts depends on three sources: the object chosen, either a true or apparent good; the intention of the subject who acts, that is, the purpose for which the subject performs the act; and the circumstances of the act, which include its consequences.”
USCCB Catechism: “Every moral act consists of three elements: the objective act (what we do), the subjective goal or intention (why we do the act), and the concrete situation or circumstances in which we perform the act…. All three aspects must be good — the objective act, the subjective intention, and the circumstances — in order to have a morally good act.”
There is no other basis for the morality of an act apart from these three fonts. For any act to be moral, all three fonts must be good. If any one font is bad, the act is immoral, even if the other fonts are good. Each and every knowingly chosen act is judged solely by the three fonts of morality. The three fonts of morality are the sole determinant of the morality of each and every knowingly chosen act, without any exception whatsoever. Whoever contradicts this teaching has overturned the very foundation of every moral teaching in the one holy Catholic and Apostolic Church.
by Ron Conte