Unless otherwise indicated, quotations are cited from the 1984 Penguin Books reprint.
Work as if you were in the early days of a better nation.
Variants on this epigraph appear in other books by Alasdair Gray; one of them, "Work as if you live in the early days of a better nation", is now engraved on a wall of the Scottish Parliament building.  They are all loose paraphrases of a couplet from Dennis Lee's "Civil Elegies":
And best of all is finding a place to be
in the early days of a better civilization. 
I asked the headmaster of literature, "Why are there so many headmasters and so few poets? Is it easier for you to train your own kind than ours?" He said, "No. The emperor needs all the headmasters he can get. If a quarter of his people were headmasters he would be perfectly happy. But more than two poets would tear his kingdom apart."
"Five Letters from an Eastern Empire", p. 88.
A goodpoem is a tautology. It expands one word by adding a number which clarify it, thus making a new word which has never before been spoken. The seed-word is always so ordinary that hardly anyone perceives it. Classical odes grow from and or because, romantic lyrics from but or if. Immature verses expand a personal pronoun ad nauseam, the greatestworks bring glory to a common verb.