All forms of imagination, including what we call past and future, live in the apparent world of the mind's eye.
Think of the song happy birthday. You can hear the tune, yet solely within the mind's eye, not with your actual ears.
Recall what a friend of yours looks like. You can see their face and body, even though you're not actually looking at them with your eyes.
Now imagine the smell of lavender, notice the capacity to "know" the scent, without presently smelling it.
It. Feels. So. Real. And yet, there is literally no substance to it.
Presence is the capacity to be here, now, rather than lost in imagination; it’s the power to discern between what’s real and what’s not.
Suffering is only possible when we are recalling or projecting in the mental realm and confusing these dreams (suffering = nightmares) of past and future for what is real, now.
"To the dreamer, it isn't a dream."
- Byron Katie