Albert Einstein, “Investigations on the Theory of Brownian Motion”, Annalen Der Physik, 1905, volume 19, page 371-381 was a book by Albert Einstein on botanist Robert Brown’s microscopic observations. Robert Brown was a naturalist on the HMS Investigator a survey ship; and, (similar to naturalist Charles Darwin on the HMS Beagle) Robert Brown collected botanical specimens. He published his book Robert Brown, “An Account of Microscopical Observations Made…”, in 1828; and, this is what Albert Einstein wrote about in 1905.
Robert Brown observed the “random walk” of pollen granules diffusing through water under a microscope. Albert Einstein wrote in 1905 his theory of Brownian motion to prove “vital force” is not needed to explain the Brownian movement. In this paper by Albert Einstein is with other scientists who opposed “vital force”. The idea of “vital force” is that something supernatural is in all living matter. Albert Einstein showed that pollen movement is due to “fluid dynamics” and nothing else.
Albert Einstein was the final voice on two forces: “gravity” and “vital”. “Gravity”, Einstein proves is caused by curvature in space-time (Relativity): and, “Vital” is a force Einstein shows does not exist. Proving “vital force” does not exist was fundamental step in biology and biochemistry of today.