heart (n.) 2
spirit, soul, essence
Cor I.vi.55 [Cominius to Martius, of Aufidius] Their very heart of hope [or: seat, source]
H8 I.ii.1 [King Henry to Wolsey] My life itself, and the best heart of it, / Thanks you for this great care
Tim I.i.280 [First Lord to Second Lord, of Timon] He outgoes / The very heart of kindness
See also...
Discourse markers