To recognize and celebrate Steve Hawking’s 75th birthday today, here are a couple of his quotes that I enjoyed.

“I have noticed that even people who claim everything is predetermined and that we can do nothing to change it, look before they cross the road.”

“Next time someone complains that you have made a mistake, tell him that may be a good thing. Because without imperfection, neither you nor I would exist.”

“If aliens visit us, the outcome would be much as when Columbus landed in America, which didn’t turn out well for the Native Americans. We only have to look at ourselves to see how intelligent life might develop into something we wouldn’t want to meet.”

To read all the quotes from his 2010 interview with Diane Sawyer/ABC News, go to Mental Floss.