398 Prof. Leslie on the L ight of the Moon and the Planets. 
substances manifest the same property. A diamond held for a 
few minutes near the flame of an Argand lamp, and then car- 
ried into a dark room, will for a short time emit a vivid light. 
But this lustre is always white, whatever may be the colour of 
the rays absorbed, insomuch that the intervention of a red, green, 
or blue glass between the lamp and the diamond, will not alter 
the effect. 
The Moon, examined by a good telescope, has absolutely the 
appearance of an incinerated mass. Some circular cavities and 
round protuberances shine with remarkable efflulgence, while 
very wide and smooth plains seem to have nearly lost the phos- 
phorescent property, and to have a brown or dark shade. The 
Moon being fifty times smaller than our globe, with only the 
seventieth part of its attractive power, has five-sevenths of the 
Earth’s density, and is consequently about four times denser than 
water. She may then consist of stony matter similar to the terres- 
trial composition. But it would be rash to pursue the parallel 
any farther. No disposition is more fallacious than the propen- 
sity of mankind to personify all nature, and trace our image, 
habits, and operations in strange and unknown objects. Every 
spot of the universe that has been explored, teems with animation, 
— the land, the sea, and the air — are all tenanted by some kinds 
of living creatures. But what right have we to suppose that the 
inhabitants of the Moon have any relation or similitude to our- 
selves P There is no appearance of any water in the moon, nor 
of an atmosphere. But the former might be detected by its 
optical effects, and the latter by the occultation of the fixed stars. 
If any creatures, therefore, live in the moon, they must be very 
different from the occupiers of this Earth. We may perhaps 
be allowed to conjecture, that the surface of the Moon, appa- 
rently marked by numerous groups of extinct volcanos, is only 
recovering from its incinerated state, and advancing slowly into 
a condition fit for the growth of the vegetable tribes. A care- 
ful comparison of telescopic observations, after long intervals of 
time, might perhaps discover this progress of amelioration, and 
ascertain the gradual darkening of the surface, which must fol- 
low the decay of the lunar phosphorescence. 
The ancient cosmologists and their poetical expounders, en- 
tertained a whimsical opinion, that the stars are fed by the hu- 
