pink floyd

What the hell do the lyrics for all of the Pink Floyd songs mean anyway?  I've never been a student of allegory, metaphor or simile, but it occurred to me this morning that I actually don't have a fucking clue what their songs mean, and I've been listening to them for about twenty years.  The irony of "For millions of years, mankind lived just like the animals.  Then something happened which unleashed the power of our imagation.  We learned to talk", delivered by Stephen Hawkings (who can't talk) isn't lost on me.  Nor is the fact that I'm asking this question.  Google and I have a date later it would seem.