The edifice of science not only requires material, but also a plan. Without the material, the plan alone is but a castle in the air-a mere possibility; whilst the material without a plan is but useless matter.
Dmitri MendeleevThe elements, if arranged according to their atomic weights, exhibit an apparent periodicity of properties.
Dmitri MendeleevKnowing how contented, free, and joyful is life in the world of science, one fervently wishes that many would enter its portals.
Dmitri Mendeleev