What is the significance of the symbols in The Stranger?

Symbolism in tends to
be occupied with either absurdism or its opposite.

For example, the sun which
irritates Mersault's eyes and gleams off the blade of the Arab represents nature. Considering
how the sun acts as an irritant and a factor in Mersault's murdering the Arab, nature (or
perhaps more accurately, environment) is presented as the central force determining human
actions. If the day had been cloudy, then Mersault likely would not have been compelled to kill
the other man.

Both the courtroom in which Mersault is tried and the crucifix
offered to him by the prison priest represent society's insistence upon rationality, tradition,
and order. The occupants of the courtroom think Mersault is a monster because he does not
ascribe rational reasoning to his actions. The priest tries to get Mersault to accept the idea
that the universe is governed by the rational laws of a benevolent and just deity. Mersault's
rejection by the courtroom and his rejection of the priest's crucifix illustrate his embracing
of an absurd, meaningless view of life.