No matter how fine your suit and your shoes, you will remind everyone that you are not yet a grownup man by wearing them with your old college knapsack, in its nasty, nylon glory.
A suit is just a suit: a practical garment, not a ceremonial robe; it can be worn out to dinner with friends or for a visit to an art gallery. Its beauty and craftsmanship are utterly wasted if you think of it as something magical and symbolic.