How we cite our quotes: (Line)
Quote #1
Time present and time past
Are both perhaps present in time future,
And time future contained in time past. (1-3)
Right off the bat, the speaker wants you to understand and accept the fact that the past, present, and future are not three different times. They're all the same, because time is a single seamless fabric. It's not clear at this point why this is so important, but as you read on, you realize that the speaker thinks our normal conception of time makes us sad by taking us away from the present moment.
Quote #2
I can only say, there we have been: but I cannot say where.
And I cannot say, how long, for that is to place it in time. (70-71)
The speaker wants to show us the experience of spiritual enlightenment, but he has a really tough time doing this in words. This is because our language doesn't really provide us with the tools we need to talk about an experience that's basically beyond words. The speaker can only say that the spiritual experience is "there," and point toward it, though he can't say much more than this. He also can't say how long we've been in this place, because that will just put it into our normal concept of time, which is not how a spiritual experience works. It's something that takes place in a sort of unending present moment, where clocks aren't welcome.
Quote #3
Yet the enchainment of past and future
Woven in the weakness of the changing body
Protects mankind from heaven and damnation
Which flesh cannot endure. (81-84)
The reason we worry so much about the past and future is because we know our bodies are always getting older, and this concerns us because it means we're going to die someday. It's because our time on Earth is limited that we obsess over the past and future. But if we're going to start living in a constant spiritual present moment, we're going to have to get over this fear of death and aging.