Therapy now means "treatment of illness, injury, or disability" or more specifically, "psychotherapy", or it can refer to any "healing power or quality"—as in the therapy of fresh air and sun.

It comes from the New Latin therapia, which is modelled on the ancient Greek word θεραπεία. All of this information is readily available in the indispensable online American Heritage Dictionary.

We can go one step further, however. Greek θεραπεία is an abstract noun based on the word θεράπων—a "henchman" or "attendant". "Henchman" has acquired unfortunate connotations—as it now indicates not merely a "loyal and trusted follower or subordinate" but especially "one who engages in unscrupulous or criminal behavior on the leader's behalf" (ahdictionary.com s.v. "henchman").

Its original significance, however, was highly dignified. The OED explains:

In the earliest documentation, the word [henchman] is applied to a small number of personal attendants to Edward III who appear to have served in a role similar to that of Groom of the Chamber (Groom of the Chamber at groom n.1 3c). Throughout the 15th and 16th centuries the English royal household continued to include a group of henchmen, typically boys and young men from noble families undergoing a chivalric education, until the position was abolished by Elizabeth I (cf. quot. 1565). Attendants designated by this name are also recorded in the households of noblemen, knights, and magnates. For further information on this history of the role see C. M. Woolgar Great Househ. Late Medieval Eng. (1999) iii. 41–2.

If you dig deeper in the OED, you'll see that "henchman" seems to have indicated in its earliest use a specific kind of servant but then became a title for a certain group of young noblemen.

That combination of service and great dignity exactly captures the force of Greek θεράπων.

A particular adjective, of which Homer was specially fond, is particularly apt for the noun θεράπων. The adjective is αἰδοῖος, which has a wonderful double significance—meaning both "having a claim to regard or compassion" and "showing reverence or compassion." This double significance of the adjective is due to a similar double significance in the noun from which it derives, αἰδώς, which is both "reverence, awe, respect" and "that which elicits respect"—"majesty" or "awesomeness".

The idea behind both words is that the showing of reverence or compassion and the receiving of it are as two sides of one coin. Duly revering a person or thing is inherently "reverend"—itself a deed worthy of respect.

Such associations are important for understanding a contrast which Socrates makes in Plato's dialogue Gorgias between therapeia and another condition or action, which is usually translated into English as "flattery". The Greek word is κολακεία, formed from the noun κόλαξ.

The specific idea indicated by the words κόλαξ and κολακεία is that of the gratification of others for one’s own personal gain. E. R. Dodds suggests in his magnificent commentary on the dialogue the words "bum-sucker, lickspittle, and toad-eater".

In the next several newsletters, I will trace Socrates's elaborate distinction between these two qualities, and their corresponding actions, throughout the Gorgias. The next chapter will be a sketch of the historical person for whom the dialogue is named, the Sicilian professional speaker, Gorgias of Leontini.