Why was Hermann von Helmholtz’s measurement of nerve impulses important for physiology?

Hermann von Helmholtz’s measurement of nerve impulses was a landmark achievement in physiology because it provided empirical evidence that refuted the prevailing doctrine of vitalism.1

At the time, many physiologists, including Helmholtz’s teacher Johannes Müller, argued that the nerve impulse was a "vital function" governed by a mysterious, non-physical "vital force" that could never be measured or reduced to mechanical laws. In 1850, Helmholtz successfully measured the speed of the nerve impulse—finding it to be a relatively slow 90 feet (27 meters) per second—using a myograph he invented.1

This discovery was significant because it demonstrated that the nerve impulse was a measurable physical process rather than an intangible force. By showing that the impulse could be studied through experimental observation, Helmholtz supported the view that nervous conduction involved the rearrangement of ponderable molecules, thereby advancing the application of classical mechanics and physical laws to the study of living organisms.1