FALLACIES OF OBSERVATION. 345 



tabula in templo ei monstraretur eorum, qui vota solverant, 

 quod naufragii periculo elapsi sint, atque interrogando preme- 

 retur, anne turn quidem Deorum numen agnosceret, qusesivit 

 denuo, At uU sunt illi depicti qui post vota nuncupata peri- 

 erunt ? Eadem ratio est fere omnis superstitionis, ut in Astro - 

 logicis, in Somniis, Ominibus, Nemesibus, et hujusmodi ; in 

 quibus, homines delectati hujusmodi vanitatibus, advertunt 

 eventus, ubi implentur ; ast ubi fallunt, licet multo frequentius, 

 tamen negligunt, et prsetereunt" And he proceeds to say, that 

 independently of the love of the marvellous, or any other bias 

 in the inclinations, there is a natural tendency in the intellect 

 itself to this kind of fallacy ; since the mind is more moved by 

 affirmative instances, though negative ones are of most use in 

 philosophy ; " Is tamen humano intellectui error est proprius 

 et perpetuus, ut magis moveatur et excitetur Affirmativis quam, 

 Negativis ; cum rite et ordine ffiquum se utrique prsebere de- 

 beat; quin contra, in omni Axioinate vero constituendo, major 

 vis est instantise negative." 



But the greatest of all causes of non-observation is a pre- 

 conceived opinion. This it is which, in all ages, has made the 

 whole race of mankind, and every separate section of it, for 

 the most part unobservant of all facts, however abundant, even 

 when passing under their own eyes, which are contradictory to 

 any first appearance, or any received tenet. It is worth while 

 to recal occasionally to the oblivious memory of mankind some 

 of the striking instances in which opinions that the simplest 

 experiment would have shown to be erroneous, continued to 

 be entertained because nobody ever thought of trying that 

 experiment. One of the most remarkable of these was exhi- 

 bited in the Copernican controversy. The opponents of Coper- 

 nicus argued that the earth did not move, because if it did, a 

 stone let fall from the top of a high tower would not reach the 

 ground at the foot of the tower, but at a little distance from it, 

 in a contrary direction to the earth's course ; in the same 

 manner (said they) as, if a ball is let drop from the mast-head 

 while the ship is in full sail, it does not fall exactly at the foot 

 of the mast, but nearer to the stern of the vessel. The Coper- 

 nicans would have silenced these objectors at once if they had 



