"I have always been convinced that the universe is governed by laws that are discoverable through observation and experiment."

"The greatest value of a scientific discovery is not so much in the discovery itself as in the stimulus it provides for further investigation."

"My main interest is to help my country, Russia, develop its industrial capacity."

"The periodic law is now so firmly established that no one can gainsay its fundamental truth."

"I consider it my duty to warn against this tendency to make a science of alchemy."