What are gps systems and what are they good for?

Famous quotes containing the word systems:

    What avails it that you are a Christian, if you are not purer than the heathen, if you deny yourself no more, if you are not more religious? I know of many systems of religion esteemed heathenish whose precepts fill the reader with shame, and provoke him to new endeavors, though it be to the performance of rites merely.
    Henry David Thoreau (1817–1862)