"I Second That Emotion" is a song written and performed by soul group Smokey Robinson and The Miracles, released in 1967 on Tamla, a division of Motown Records. It went to #4 on the pop charts, making it their most successful song at the time, although it would later be superseded by their only #1 song, The Tears of a Clown. It would become a staple of oldies and pop radio, and is a classic of soul music.
The song is written as a mid-tempo ballad, with alternating verse and chorus. It is a little under three minutes long, and structurally it is a pretty typical song. For me, the appeal of the song comes from the alternating verse and chorus, which present alternative thoughts of the singer. In the verses, he warns a woman that if her affection is false, he isn't interested in her, because "a taste of honey is worse than none at all". In the chorus, however, he switches to a more optimistic thought, saying that if the woman is truly interested in being his partner, "I second that emotion".
Grammatically speaking, the song interests me, and I think that the grammar selected helps set the tone for the song. English has four types of conditionals, numbered (slightly confusingly) zero to third. Zero and one are used to talk about real possiblities, while the second and third are used to talk about unreal situations. In songs, the first are usually used optimistically, while the second two are often used to discuss sorrow or regret. This song uses the zero conditional: the if statements are treated as simple hypothetical possibilities. The singer believes that the woman having genuine feelings for him is a likely probability. Despite the warnings he is giving himself in in the verses, the chorus switch to a more optimistic note, stating that true love, if not assured, is still real.
I think the music and lyrics both communicate the same message, and this is the key to the song's appeal. It is neither a syrupy statement of total love nor a pessimistic look at love. The lyrics and the music reflect a very real mixture of the caution and optimism that people have when facing romantic relationships. And I think that gives the song an authenticity that has allowed it to become a classic.