'half a page of scribbled lines' is a line from the Pink Floyd song Time that immortally captures the failure to find immortality. It comes at the end of the couplet:

Every year is getting shorter, never seem to find the time
Plans that either come to naught or half a page of scribbled lines

The Dark Side of the Moon lyrics are much more vague than those of The Wall. The Wall's lyrics tell a very specific story. The lyrics on The Dark Side of the Moon, where the song Time comes from, are more about general human emotions. You could imagine that they are about The Wizard of Oz, but you could as well imagine that they are about your own life. The lyrics to the song Time, and this lyric, a single half-line, seem to be something most people can sympathize with. If I mention "half a page of scribbled lines" to most people, they usually understand the feeling I am trying to convey.

When I was 16, I had just left my high school, such as it was, hoping to chart out a new path for myself. This came to many days, weeks and months of isolation, reading and writing furiously. I filled up many notebooks with attempts at writing poetry and fiction. And now, ten years have passed, and I don't know if any of my desire to capture the essence and feeling of my life have come to anything more than the type of livejournal jottings that will be quickly forgotten. I must now face, after ten years, the feeling that I am procrastinating my life away, and will never encounter the greatness I hope for.

It is somewhat ironic, that Pink Floyd, in an attempt to convey this sense of hopelessness at doing anything of lasting value, have produced a phrase that so totally and perfectly captures a human feeling, and will probably be used to communicate the feeling of futility for a long time.