What is the origin of the phrase 'heart of hearts'?

Answer 1

The origin of the word heart is Old English heorte, of Germanic origin; related to Dutch hart and German Herz, from an Indo-European root shared by Latin cor, cord- and Greek ker, kardia.

Answer 2

; heart : O.E. heorte, from P.Gmc. *khertan- (cf. O.S. herta, O.N. hjarta, Du. hart, O.H.G. herza, Ger. Herz, Goth. hairto), from PIE *kerd- "heart" (cf. Gk. kardia, L. cor, O.Ir. cride, Welsh craidd, Hittite kir, Lith. širdis, Rus. serdce "heart," Breton kreiz "middle," O.C.S. sreda "middle"). Spelling with -ea- is c.1500, by analogy of pronunciation with stream, heat, etc., but remained when pronunciation shifted. Most of the figurative senses were present in O.E., including "intellect, memory," now only in by heart. Hearty is c.1380; heart-rending is from 1687. Heartache was in O.E. in the sense of a physical pain, 1602 in sense of "anguish of mind;" heartburn is c.1250. Broken-hearted is attested from 1526. Heart-strings (1483) was originally literal, in old anatomy theory "the tendons and nerves that brace the heart." Heartless (c.1330) originally was used with a meaning "dejected;" sense of "callous, cruel" is not certainly attested before Shelley used it so in 1816. Heartland first recorded 1904 in geo-political writings of H.J. MacKinder.

Answer 3

It's from Hamlet by Shakespeare. IN Act 3, Scene 2, Hamlet says, "In my heart's core, ay, in my heart of heart, as I do thee."

:D