From May sidebar.

Opportunity is missed by most people because it comes dressed in overalls and looks like work.
~Thomas Edison

Opportunity is a haughty goddess who wastes no time with those who are unprepared.
~George S. Clason

Too often, the opportunity knocks, but by the time you push back the chain, push back the bolt, unhook the two locks and shut off the burglar alarm, it’s too late.
~Rita Coolidge Singer