Hávamál (No1)

1:
At every door-way,
ere one enters,
one should spy round,
one should pry round
for uncertain is the witting
that there be no foeman sitting,
within, before one on the floor

When you are out in the public place, look around and pay attention, because you do not know where enemies can be. If you see them before they see you, you can avoid them or have the element of surprise.