The answer to this tricky question is human being. In this
question, morning represents the child or the early age of the human. So in the
early age or during the time when a human being is a baby it crawls on its all
fours. The noon represent the middle age of the person when he or she walks on
their both legs. At night or in the old age a human being walks on their two
legs and takes the support of a cane which acts as the third leg.
