The vision of regarding the unity of the sciences was so great that he hardly knew when he was doing psychology, physiology, or physics. He believed there were no mysterious forces or unknowable energies that activate the organism.

Hermann Ludwig Ferdinand von Helmholtz

Explanation: Hermann Ludwig Ferdinand von Helmholtz born  August 31, 1821 was a physician and physicist. Known for the philosophy of science as a philosopher, also known in the field of physiology, psychology and physics for  conservation of energy, thermodynamics, sensation of tone, perception of sound etc. Because of his vast knowledge, he hardly knew when he was doing psychology, physiology, or physics.

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