Yılın Tabiatı Üzerine: Güneşin Dönüşü ve Gözlemin Alçakgönüllülüğü

"Year" means one revolution of the sun in the ecliptic, moving in a direction opposite to that of the universal motion, and returning to the same point assumed as the starting point of its motion. In this way, the sun includes in its course the four seasons—spring, summer, autumn, winter—and their four different natures, returning always to the point from which it commenced. According to Ptolemy, these revolutions are equal because he did not find that the apogee of the sun moves. Conversely, they are unequal according to the authors of the Sindhind and the modern astronomers, because their observations led them to believe that the apogee of the sun moves. As to the length of such a revolution in days and fractions of a day, the results of astronomical observations do not agree; they differ considerably. However, in a short space of time, this difference is barely perceptible. But in the long run, when this difference is doubled and multiplied many times and then summed into a whole, a very great error becomes manifest. Because of this, the sages have strongly recommended that we continue making observations and guard against potential errors.