It is a good lesson /though it may often be a hard one /for...

It is a good lesson /though it may often be a hard one /for a man who has dreamed of literary fame, and of making for himself a rank among the world's dignitaries by such means, to step aside out of the narrow circle in which his claims are recognized, and to find how utterly devoid of all significance, beyond that circle, is all that he achieves, and all he aims at.