You know that moment when passion and yearning collide? That explosion wiping out any remaining cells of sense and you can nothing but let your body take over? You shiver as you speak and you move in auto-pilot to afterwards forget everything about the event but the feeling it gave you.
You will then suddenly find yourself in a different moment, reminding you of this very emotion and you will quiver. Quiver from joy, from the gratefulness and smugness that you got to feel those feelings. And then someone talks, waking you up from your momentary lapse of a trance where you traveled through time to relive that magnificent and raw explosion.
Perhaps this is daydreaming in its purest form?