What the lexicon says. καρδία (kardia) is introduced in Abbott-Smith with the note "[in LXX chiefly for לֵבָב, לֵב]", that is, when Greek translators of the Hebrew Bible met lev or levav, this is the word they normally reached for. The definition proper reads: "In a psychological sense, the seat of man's collective energies, the focus of personal life, the seat of the rational as well as the emotional and volitional elements in human life". Strong's: "The heart, i.e. (figuratively) the thoughts or feelings (mind); also (by analogy) the middle." It appears in 153 verses.
What the text does with it. "And the peace of God, which passeth all understanding, shall guard your hearts and your thoughts in Christ Jesus" (Philippians 4:7, ASV), the tagged text shows kardia behind "hearts", and two different mind-words behind the other two nouns, which is the subject of the next entry.
Sources: Philippians 4:7; TBESG entry G2588 (Abbott-Smith); Strong's Greek Dictionary (1890), entry G2588; ISBE 1915, "Heart" (J. I. Marais).
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