We must again emphasize that an incomplete truth is in no way an error, nor can it be termed a “relative” truth. An incomplete truth is as true as a complete truth though it calls for completion: the statement that the morally good is a value, and not something merely subjectively satisfying, is true — though it is incomplete because it does not finger the specific nature of moral values, what distinguishes them from intellectual and aesthetic values. Numerous examples of incomplete truths could be given, all absolutely true notwithstanding their incompleteness.
The act of completing incomplete truths may take diverse forms. It may appear as a further differentiation, a greater specification, the perception of new distinctions within the framework of an already conquered truth. It may take the form of a discovery of another aspect of a being. Sometimes it involves delving deeper into a realm of being, continuing former insights, but seeing new complexities and ramifications. This kind of development can sometimes be found in the lifework of an individual philosopher, as well as in the entire history of philosophy.
Dietrich von Hildebrand, Trojan Horse in the City of God (Chicago: Franciscan Herald Press, 1967), 57.
[See also this post.]