proverbs 4 almost presents wisdom as this light, if you walk with it, you won’t stumble 
you'll be able to see because wisdom is your guide.
people who walk in evil allow darkness to be their guide, so they stumble because they can’t see.

' avoid it, do not go on it; turn away from it, and go on.'  v15
look at the urgency of this verse through the use of imperatives, ‘avoid’, do not’, ‘turn away’ and ‘go’. 
the rapid sequence of commands suggests that this must be done quickly.  

' for they cannot sleep unless they cause harm; they are robbed of sleep until they make someone stumble.' v16
this is interesting, when we walk in darkness you don’t feel at peace until you wreck someone else’s peace.