Mark (not his real name) couldn't see the whole picture. In fact, he was having trouble seeing at all. His eyes were red and irritated. But he never suspected that this irritation was related in any way to the mysterious redness on his face.
"I woke up one morning and my eyes were sore," Mark said. "It felt like I had something in them that I couldn't get out." Despite the irritation he went to work anyway.