What is physical exertion?

Famous quotes containing the words exertion and/or physical:

    Knowledge is not a passion from without the mind, but an active exertion of the inward strength, vigour and power of the mind, displaying itself from within.
    Ralph J. Cudworth (1617–1688)

    The vanity of the sciences. Physical science will not console me for the ignorance of morality in the time of affliction. But the science of ethics will always console me for the ignorance of the physical sciences.
    Blaise Pascal (1623–1662)