I Heart Silphium

So, where does the heart symbol come from anyhow?  John Riddle, a medical historian, is cited in The Age (Australia) for the idea that it derives from the heart-shaped seed pods of the silphium plant, which was used in ancient times as a contraceptive, and was thus an effective symbol for love...

Classical literature is rife with references to silphium. The Roman bard Catullus alludes to its sexual properties in one of his love poems. When asked how many kisses it will take to satisfy him, he says: "As many as the grains of the sand in the desert near Cyrene where silphium is gathered."

Others have different ideas...