Nikola Tesla

“ As regards the currents of very high potential differences, which were employed an my experiments, I have never considered the current's strength, but the energy which the human body is capable of receiving without injury, and I have expressed this quite clearly on more than one occasion. For instance, I stated that "the higher, the frequency the greater the amount of electrical energy which may be passed through the body without serious discomfort." ”

“ I stated in my paper, before mentioned, that it is an undeniable fact that currents of very high frequency are less injurious than the low frequency currents, but I have also taken care to prevent the idea from gaining ground that these currents are absolutely harmless, as will be evident, from the following quotation: "If received directly from a machine or from a secondary of low resistance, they (high frequency currents) produce more or less powerful effects, and may, cause serious injury, especially when used in conjunction with condensed." ”

“ I would here point out that one is apt to fall into the error of supposing that the spark which is produced between two points on a conductor, not very distant from each other, is due to the impedance of the conductor. ”