The theoretical side of ...

The theoretical side of physical chemistry is and will probably remain the dominant one; it is by this peculiarity that it has exerted such a great influence upon the neighboring sciences, pure and applied, and on this ground physical chemistry may be regarded as an excellent school of exact reasoning for all students of the natural sciences.
 Svante Arrhenius

Quotes from the same author

Is the mean temperature of the ground in any way influenced by the presence of heat-absorbing gases in the atmosphere?
 Svante Arrhenius