15 The word “heart” proves its value for philosophy and theology in their efforts to reach an integral synthesis. Nor can its meaning be exhausted by biology, psychology, anthropology or any other science. It is one of those primordial words that “describe realities belonging to man precisely in so far as he is one whole (as a corporeo-spiritual person)”. It follows that biologists are not being more “realistic” when they discuss the heart, since they see only one aspect of it; the whole is not less real, but even more real. Nor can abstract language ever acquire the same concrete and integrative meaning. The word “heart” evokes the inmost core of our person, and thus it enables us to understand ourselves in our integrity and not merely under one isolated aspect.
Source: Dilexit Nos (Vatican.va)