He who meanly admires mean things is a Snob.

The sentence defines snobbery as a failure of judgment and integrity: the “snob” is not simply someone who likes refined things, but someone who admires what is base or trivial precisely because it is socially sanctioned. “Mean” here carries a double force—petty in value and ignoble in spirit—so the admirer is diminished by the act of admiration. Thackeray’s point is that taste becomes moral when it is driven by servility to status rather than by discernment. The line compresses a broader Victorian satire: social hierarchies persist not only through power, but through the eager complicity of those who worship their symbols.