If you see a hawk on a bough at field's edge beyond the corner you should have turned maybe it's a sign to go on.
Such as during an improvisation on Flamingo or I've Got You Under My Skin you play in the wrong key or mode completely maybe it's a sign to go on, in the wrong key.
Or when my sons cry not wanting to be alone, I'm upstairs writing or just enjoying trees in every direction it too may be a sign to go on alone.