Greeting cards are a great way to find titles for love songs. That's how the British singer-songwriter David Martin discovered this one.

His wife, who worked at a card store, showed him one with a frown and teardrop on the cover, and the words "Can't Smile Without You."

"I was immediately drawn to the slogan and during the drive home from Hampstead to Harrow, a journey of about 30 minutes, the song was written," he explained in the liner notes of Manilow's anthology The Complete Collection and Then Some.

"When I first heard Barry's recording of the song, I realized that his injection of key changes coupled with the feeling of voice made the song speak volumes."

David Martin completed this song with his writing partners Chris Arnold and Geoff Morrow, and released the original version as a single in 1975.

His version didn't get much attention, but in 1976 both the Carpenters and Engelbert Humperdinck recorded it.

Neither of these versions were released as singles, so Barry Manilow's label boss, Clive Davis, had him take a crack at it.

Released as the first single from his 1978 album Even Now, it was a winner, going to #1 on the Adult Contemporary chart and #3 on the Hot 100.

The David Martin original has a string arrangement but is pretty basic. When Manilow heard it, he thought it was too simple and also too commercial. Clive Davis insisted he record it, so Barry Manilowized it, ramping it up with a lush, campy production that builds to a rousing finale.

"I decided that I would treat it with a big smile; like a vaudeville piece, with lots of key changes, a whistle in the intro and a real take-home ending," he said in The Complete Collection and Then Some. "I had even made plans to include a tap dance solo!"

Manilow, who produced the song with Ron Dante, decided against the tap dancing but went with the whistling to open the song, which in the original is just keyboard notes.

"I realized that the song was absolutely irresistible and decided to treat it with the same smile, but less silly and we made a record of it that I'm still proud of to this day," he added.

In concert, this is a showstopper for Manilow. He would often start the song at the piano and then get up midway through, moving to the front of the stage to lead the crowd in a singalong.

At some shows, he would bring a (female) fan on stage to sing it with him. This was great for the fan, not so much for the audience if she wasn't a good singer, which was often the case.

Manilow ruled the realm of soft rock at this time. Even Now, which also contains "Copacabana (At The Copa)," is his best-selling studio album. "Can't Smile Without You" was his eighth of 13 #1 Adult Contemporary hits.