OF NATURAL HISTORY. 193 



horizontal direction. During the night, on account of the 

 darknefs, we have no proper idea of diftance, and, of courfe, 

 judge of the magnitude of objects folely by the largenefs of 

 the angle or image formed in the eye, which necefTarily pro- 

 duces a variety of deceptions. When travelling in the 

 night, we are liable to miflake a bufli that is near us for 

 a tree at a diftance, or a diftant tree for a bufh which is at 

 hand. When benighted in a part of the country with which 

 we are unacquainted, and, of courfe, unable to judge of the 

 diftance and figure of objeds, we are every moment Hable to 

 all the deceptions of vifion. This is the origin of that dread 

 which fome men feel in the dark, and of thofe ghofts and 

 horrible figures which fo many people pofitively aftert they 

 have feen in the night. Such figures are commonly faid to 

 exift in the imagination only ; but they often have a real ex- 

 iftence in the eye ; for, when we have no other mode of re- 

 cognifing unknown obje£ls but by the angle they form in 

 the eye, their magnitude is uniformly augmented in propor- 

 tion to their vicinity. If an obje6l, at the diftance of twenty 

 or thirty paces, appears to be only a few feet high, its height, 

 when viewed within two or three feet of the eye, will feem 

 to be many fathoms. Objects, in this fituation, muft excite 

 terror, and aftoniftiment in the fpeflator, till he approaches 

 and recognifes them by a£l:ual feeling ; for the moment a 

 man examines an obje£l properly, the gigantic figure it aftum- 

 ed in the eye inftantly vanifhes, and its apparent magnitude 

 is reduced to its real dimenfions. But if, inftead of approach- 

 ing an objea of this kind, the fpedlatcwr flies from it, he re- 

 tains the idea which the image of it formed in his eye, and 

 he may affirm with truth, that he beheld an objeft terrible 

 in its afpe<n:, and enormous in its fize. Hence the notion of 

 fpeares, and of horrible figures, is founded in nature, and 

 depends not folely on imagination. 



