Neither symboliste nor decadent, he was a pessimist in so far as that character applies to a man who looks at the worst contingencies as well as the best in the human condition.
Youth dies. Life hurts. Love warms. Understanding heals. The wounds and balms of the human condition are so commonplace that men eventually experience them without noticing.
Christian theology traditionally sees three elements of the human condition that are in need of transformation: sin (estrangement from God), evil (estrangement among humans), and death (mortality, and our estrangement from nature).