A time is a time span (for example, 1900-1920 is a time)
So, we teach our children something (our message is what we have taught our children) they will remember in the future (the future we might not see because we will die of old age).
Hi,
I think in this way:
Children are the living messages whom/that we send to a time which/that we will not see.
In other words, we send CHILDREN & we will not see a TIME.
Wishes,
Morteza
Living is used because you could send a message in the form of a note, a book, a poem, but your children are actually alive, even though you’re not. So, by emphasizing that the message is “living” there’s an implication that a part of you is alive as well.