What are the "cockles of your heart" and
why do they need warming?
The meaning can be interpreted as the "cockles of the heart" are warmed by an emotional experience that exposes the tender and warm side of the human experience, thus opening of the "heart".
The expression turns up first in the middle of the seventeenth century, and the earliest form of the idiom was 'rejoice the cockles of one’s heart'.
Some say cockles is a medical term. Cockles are a type of bivalve mollusc. They are frequently heart-shaped (their formal zoological genus was at one time Cardium, of the heart) with ribbed shells.The heart is
composed of various parts that work in unison to pump blood throughout the
body. One of the parts of the heart is
called a ventricle. Anyway, the Latin tem for the heart's ventricles is
"cochleae cordis". Could "cockle" be a corruption of the
medieval Latin word for heart - cochleae cordis?
The cockles of your heart are its ventricles and
thus by extension, the innermost depths of one’s heart or emotions. The word
comes from the Latin phrase cochleae cordis, meaning ‘ventricles of the heart.’
—Morris Dictionary of Word and Phrase Origins
My thanks to
http://www.wordwizard.com/phpbb3/viewtopic.php?f=7&t=20208 for their forum
on this topic that helped to clear up some of the confusion.