Patho-logy

The hyphenation in the title was intentional. Pathology commonly refers to the science of the study of disease. The suffix "logy" cannotes study or persuasion, and my inference: the root "patho" or some derivative of the word implies disease or maladaption or compulsive aberration. Yet, when I see the word in all its hues, pathetic, pathological etc., I fail to reconcile the lexical foundation of the word patho.

Help appreciated.