In Act 2 Scene 3 of Twelfth Night Feste enters the scene to have a drink and share some jokes with Sir Toby and Sir Andrew, who are both by this stage very drunk. Sir Toby requests a song from Feste, and this is seconded by Sir Andrew amidst a paragraph's worth of meaningless gibberish that he spews forth in his intoxicated state.
Feste asks of the two, "Would you have a love song, or a song of good life?" The answer comes back from both as a love song, and this is indeed one of the three main themes of the song. The word itself is used a lot throughout the song, although it seems in fact to be more of a tool to get to the real message. The song is in an 'easy-to-hear' rhyming pattern and has an even rhythm, which is of course necessary for a song.
Each verse begins with an attention-grabbing question, which is then answered later on.
For example, references to love include, 'O stay and hear, your true love's coming', 'Journeys end in lovers meeting', and 'What is love? 'Tis not hereafter'. Now at first these may seem to make the verse into what could be called a love song, but looking carefully at the extracts, and perhaps more importantly the lines following them, it is evident that love is only briefly mentioned before the topic moves back to a different theme, having reinforced this second theme by use of the idea of love. Thus 'love' is in effect only an example (which, to a point, could probably just as well be anything else) used as a basis for the second theme.
It does, however, relate to one of the main themes of the play quite well, as love is something...