I assume you're speaking of the lyrics, not the melody or the chords. I think melodies just slip one's head, I don't recall ever starting out to learn a melody. If the melody hasn't already wormed its way into my head, I will never realize I want to learn the piece. Like many people, I began by memorizing chord progressions---I still need to do that for jazz tunes---but the chords for most folk, old-timey, bluegrass and blues tunes are usually predictable from the melody alone so I usually don't bother looking them up.

Lyrics are another problem altogether. I've often spent considerable time learning lyrics to songs. Sometimes I learn them by osmosis over long years and sometimes I write them down and take them with me everywhere singing constantly to myself or perhaps aloud as the occasion permits. Sometimes I'll go for years thinking that I should learn a particular song and when I finally sit down to do it, I discover that the job is nearly done. My wife and daughters complain that I can remember the words to a long ballad from thirty years ago but I can't remember what happened yesterday. (Luckily, they haven't asked me anything about today.)

My real problem is remembering that I know a song---remembering that the song exists. If someone can name a song, I may be able to perform it but if I'm just asked to sing a song, I draw a blank every time. Sometimes I make lists of all the songs I might be able to perform. These lists are never exactly the same but they usually wind up with two or three hundred songs. I'm still adding to the list but I'm also starting to forget some. I guess Sir Arthur Conan Doyle was right.

      - Mark