imaginary lines which have been invented, and are only supposed for the better improvement of that science.
§180. Arithmetic is the easiest, and consequently the first sort of abstract reasoning, which the mind commonly bears or accustoms itself to: and is of so general use in all parts of life and business, that scarce anything is to be done without it. This is certain, a man cannot have too much of it, nor too perfectly: he should therefore begin to be exercised in counting, as soon, and as far, as he is capable of it; and do something in it every day, till he is master of the art of numbers. When he understands addition and subtraction, he then may be advanced farther in geography, after he is acquainted with the poles, zones, parallel circles, and meridians, be taught longitude and latitude, and by them be made to understand the use of maps, and by the numbers placed on their sides, to know the respective situation of countries, and how to find them out on the terrestrial globe. Which when he can readily do, he may then be entered in the celestial; and there going over all the circles again, with a more particular observation of the Ecliptic, or Zodiac, to fix them all very clearly and distinctly in his mind, he may be taught the figure and position of the several constellations, which may be showed him first upon the globe, and then in the heavens.