What does this sentence mean?
From 1984 by George Orwell
"What certainty had he that a single human creature now living was on his side? And what way of knowing that the dominion of the Party would not endure forever?"
I'm having trouble with the sentence structure and the meanings. Perhaps the first sentence could be read as "what certainty had he (that a single human creature now living) was on his side", but it seems to be grammatically incorrect, neither does it make sense to me.
I'd appreciate your help:)