There are plenty of good love songs out there, but what makes a love song truly great? First of all, the song must not only avoid the Scylla and Charybdis of sentimentality and cliché - not an easy task - but must go beneath the surface (the surface being where most popular music resides). Next, there must be conviction in the singer's performance, an expressive potency that moves us, maybe even sends chills down your spine. Finally, the arrangement must reinforce the spirit of the song. With that being said, I offer this list of ten great love songs -- some well known and some not so well known -- in a spectrum of styles representing the many shades of love.