Don't stumble around! This red letter wisdom is right there for everyone who reads these verses. Walk while you have the light.

John 12:35-36
Then Jesus said to them, “A little while longer the light is with you. Walk while you have the light, lest darkness overtake you; he who walks in darkness does not know where he is going.
While you have the light, believe in the light, that you may become sons of light.” These things Jesus spoke, and departed, and was hidden from them.

http://www.biblegateway.com/passage/?search=john12:35-36&version=NKJV