Every year, we celebrate English naturalist and geologist Charles Darwin and his significant contributions to science and humanity on Feb. 12, his birthday.

The objective of International Darwin Day is to inspire and encourage people across the globe to reflect and act on the principles of intellectual bravery, perpetual curiosity, scientific thinking and hunger for truth as embodied by Darwin.

Here are some inspirational quotes by Charles Darwin.

1) A man who dares to waste one hour of time has not discovered the value of life. - The Life & Letters of Charles Darwin.

2) "The mystery of the beginning of all things is insoluble by us; and I for one must be content to remain an agnostic."

3) “Ignorance more frequently begets confidence than does knowledge: it is those who know little, not those who know much, who so positively assert that this or that problem will never be solved by science." - The Descent of Man.

4) "I have called this principle, by which each slight variation, if useful, is preserved, by the term of Natural Selection."

5) “Thus, from the war of nature, from famine and death, the most exalted object which we are capable of conceiving, namely, the production of the higher animals, directly follows. There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.” - The Origin of Species.

6) “We stopped looking for monsters under our bed when we realized that they were inside us.”

7) “Intelligence is based on how efficient a species became at doing the things they need to survive.”

8) “In the long history of humankind (and animal kind, too) those who learned to collaborate and improvise most effectively have prevailed.”

9) “Besides love and sympathy, animals exhibit other qualities connected with the social instincts which in us would be called moral.”

10) “Man selects only for his own good: Nature only for that of the being which she tends.” - The Origin of Species.

Charles Darwin
A copy of Darwin's book the 'Origin of Species' is pictured in front of a life-size stone bust of Charles Darwin at London's Natural History Musuem, June 8, 2006. Getty Images/ SHAUN CURRY