Sympathy is derived from the classical Greek συμπάθεια, or fellow (συμ)-feeling (πάθεια). A solid Latin translation would be compassio. Unfortunately, whatever is exactly meant by "sympathy," to English ears "compassion," that is, "a feeling of wanting to help someone" would seem to denote merely a sub-set of sympathy.* While "sympathy" does appear (with related concepts like harmony, natural friendship, etc.) in Plato and Aristotle, it tends to be originally identified with Stoic thought; it was also taken up and developed in non-trivial ways by Plotinus, Pliny, Vetrivius, and Galen (amongst others). Use for the concept was re-discovered in the Renaissance and -- as I learned from the distinguished scholar, Ann Moyer, -- promoted not so much by Ficino, but by Erasmus and Fracastoro. Even though in Fracastoro sympathy itself had a properly atomistic explanation, the concept was banished by Descartes and lumped with the to-be-discarded occult (see Principles of Philosophy 4.187).
Given the diversity of usages of 'sympathy' within the context of very different philosophical aims, one might doubt that there is a single, underlying concept rather than a host of family resemblances. Even so, while editing a forthcoming volume on the history of the concept, I came to think that one can identify the four following features that are incorporated in most usages of the term, 'sympathy.'
- Sympathy is used to explain apparent action at a distance.
- The very possibility of sympathy presupposes that it takes place among things that are in one sense or another alike (sometimes within a single being/unity/organism) to be contrasted with the antipathy (ἀντιπάθεια) of un-alikes. I call this condition of the possibility of sympathy, "The Likeness Principle" (or TLP; recall).**
- The cause(s) of sympathy is invisible to the naked eye.
- The effect(s) of sympathy can be (nearly) instantaneous.