Astronomy without arithmetic: draw the computer on the ground. Chapter XIV of Varāhamihira's Pañcasiddhāntikā (505 CE) opens by instructing the reader to draw a level circle 180 fingers across, mark it with degrees and declinations, and stretch strings across it — then read answers (rising times, day lengths at any latitude) directly off the diagram, "without calculation, by the mere inspection" of the figure, as the 1889 translators put it. It is analog computation: the geometry does the trigonometry, fourteen centuries before nomograms became engineering practice.