"The Most Expansive, Most Brilliant Time"

"It was the most expansive, most brilliant time which Technic civilization would ever know." (Rise Of The Terran Empire, p. 143)

"The tree was growing, ever leafing, though a snake gnawed its roots. Thus was it often before on Earth, in the age of the Chun-Chiu, the age of the Delian alliance, the age of the Renaissance.
"But when a century had passed -" (ibid.)

These are not empty phrases. Poul Anderson has just presented nearly five pages of Wellsian-Stapledonian future historical writing to summarize the relationship between the Solar Commonwealth and the Polesotechnic League. (See here.) Clearly, Anderson is well informed about the three historical periods that he cites even if we ordinary sf readers are not.

In fact, he covertly invokes yet another tradition because the tree growing between the worlds while a dragon gnaws one of its roots comes directly from Norse mythology - and that tree is visited in Anderson's own fantasy novel, Operation Luna. See here.