Explain All the world's a stage with reference to the poem ‘The Seven Ages'

Explain All the world’s a stage with reference to the poem ‘The Seven Ages’.
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How can you compare human life to drama?
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What is the significance of the words, ‘entrances and exits’ in the poem, ‘The Seven Ages’?

Shakespeare compares life to a drama in which a person plays many parts as he progresses through life from early childhood to old age, the last stage of life. He enters the world at birth just like an actor enters the stage when he has to play his part, plays different roles throughout his life and finally exits from this world just like an actor who has completed his role and exits from the stage.