Winter and summer, then, were two hostile lives, and bred two separate natures. Winter was always the effort to live; summer was tropical license.
(1918)

1Syringas are ornamental shrubs.
2Pennyroyal is a mint plant; flagroot is the root of a particular herb.
3Cumuli are thick clouds.

In context, the word "society" (sentence 5) is best understood to mean

a
association

b
culture

c
gathering

d
memory

e
organization