Moses worked everyday. Hard work. Hiking through the hot desert, herding obstinate sheep from one place of famine to the next. His mind running form the past to the present, from the past to present. No future, not yet.
How many times did he pass that bush that burned but was not consumed? God did NOT speak until Moses turned aside and took notice.
What a jerk, that God. Doesn't God know how busy I am? I don't have time to be looking for burning bushes.
Remember you are dust, and to dust you shall return.
Burn, baby, burn.