Google occasionally alters its recognizable logo to celebrate specific events and holidays. These illustrations, known as Google Doodles, were actually conceived of before the company was incorporated. The first Google Doodle acted as a fun “out of the office” message when Google founders Larry Page and Sergey Brin attended Burning Man in 1998.

Since then, Google’s team of “doodlers” have created more than 2,000 illustrations for the search engine's mostly white page around the world. Examples include drawings for holidays such as Teacher’s Day to events such as the first day of fall.

In honor of Google’s 18th birthday on Sept. 27, we’ve rounded up 10 inspiring quotes from people who were featured as Google Doodles.

1. “Nothing is impossible, the word itself says 'I'm possible'! -- Audrey Hepburn

2. “The ultimate measure of a man is not where he stands in moments of comfort and convenience, but where he stands at times of challenge and controversy.” -- Martin Luther King Jr.

3. “The most effective way to do it is to do it.” -- Amelia Earhart

4. “The greatest glory in living lies not in never falling, but in rising every time we fall.” -- Nelson Mandela

5. “Find something you're passionate about and keep tremendously interested in it.” -- Julia Child

6. “There are basically two types of people: People who accomplish things, and people who claim to have accomplished things. The first group is less crowded.” -- Mark Twain

7. “You don't need anybody to tell you who you are or what you are. You are what you are!” -- John Lennon

8. “Be not afraid of greatness: some are born great, some achieve greatness and some have greatness thrust upon them.” -- William Shakespeare

9. "The best way to find yourself is to lose yourself in the service of others." -- Mohandas Karamchand Gandhi

10. “Nothing is more intolerable than to have to admit to yourself your own errors.” -- Ludwig van Beethoven