This important and incredibly famous soliloquy is delivered in Act II scene 7 in this play. In this soliloquy, Jacques compares the world to a stage, and the people that inhabit that world to players who act out a role on the stage and play many different characters during their lifetime:
All the world's a stage,
And all the men and women merely players;
They have their exits and their entrances,
And one man in his time plays many parts,
His acts being seven ages.
The more you think about this extended metaphor, the more truth we see in it as we recognise that way in which our lives are "acted out" in front of audiences. We do indeed all have our "exits and entrances," and as the soliloquy goes on to demonstrate, we all play different roles during our lifespan. As Jaques goes on to describe these "seven ages," we are forced to see how our role changes and develops as we grow older, until we reach the seventh age, with the rather terrifying image of being left with "second childness" and "mere oblivion." And on this age, the curtain falls on our life.