"The future of Russia is in its oil and its people."

"The most important thing for a scientist is to be honest with himself and with others."

"The most all penetrating spirit before which will open the possibility of tilting not tables, but planets, is the spirit of free human inquiry. Believe only in that."

"It is useful in this sense to make a clear distinction between the conception of an element as a separate homogenous substance and as a material but invisible part of a compound."

"The law of periodicity was a result of the accumulation of a large number of facts."