(This post originally appeared on the author’s own blog site in a shorter form that had a more general audience in mind.)
“As long as you say, “Bless your heart,” you can say anything you want about them afterward.”
–Comedian whose name is not remembered (bless the author’s heart).
While it can be used to express sympathy for someone who has suffered some misfortune (e.g., “Your broke your leg? Bless your heart!”), “Bless your (or “his/her/their”) heart, . . .” is often, especially in the southern US, an insult that is “softened,” typically followed by some statement as to the stupidity or wrongheadedness of the person whose heart is “blessed.” Typically, it is a statement that is trying to assert that, while “[your/her/his/their] heart is in the right place” (i.e., one is sincere in one’s motives or beliefs), the person is (sincerely!) wrong and/or thoughtless in his/her actions or application.
In Thucydides’ History of the Peloponnesian War, V.105.3 (which is an ancient account of the war between various Greek city-states led by rivals Athens and Sparta in 431-404 BCE), there is a speech of the Athenians to the inhabitants of the island of Melos, whom the Athenians wanted to defect from their alliance with Sparta. In the back and forth between the two groups, the Melosians declares that they are going to trust in the gods and in Sparta. The Athenians respond that they do not expect the gods to disfavor themselves. As far as the Melosians trusting in Sparta, they say the following: τῆς δὲ ἐς Λακεδαιμονίους δόξης, ἣν διὰ τὸ αἰσχρὸν δὴ βοηθήσειν ὑμῖν πιστεύετε αὐτούς, μακαρίσαντες ὑμῶν τὸ ἀπειρόκακον οὐ ζηλοῦμεν τὸ ἄφρον. “But of the expectation [of help] in the Lakedaimonians [i.e., Spartans] which, because of the shame [the Spartans might acquire], you believe it would be necessary of them to come to your aid, blessing your simplicity, we do not envy your drivel.”
“Simplicity” here means something like innocent sincerity. In our vernacular, it might be able to be corresponded to the metaphor of one’s “heart,” as in the motivation behind the choice. The word translated as “drivel” can be glossed more literally as “foam,” but like the English word “drivel,” which can literally mean something like slobber, it also figuratively refers to foolish talk. Put it in a form that some of the author’s Southern family might say and it comes out something like: “Bless your heart, your talk ain’t worth spit.” In other words, the Athenians think there is no way that the Spartans will be driven to help them by necessity of virtue or fear of shame, as they go on to say in the following line.
Thus, what might seem like an expression of the relatively recent past of English in America appears, at least in the general meaning of the insult form, to go all the way back to more than 2,400 years ago in Greece!