Premise: The Seven Ages of Man is a series of paintings by Robert Smirke, derived from a monologue from William Shakespeare's "As You Like It", spoken as the melancholy Jaques in Act II Scene VII. The phrase begins as "all the world's a stage". The stages referred are: infant, schoolboy, lover, soldier, justice, pantaloon and old age.
Hypothesis: The phrase begins as "all the world's a play".