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their dimensions — known objects become a standard to judge 

 of unknown — and the human figure is perhaps the first and 

 the most useful which he employs to thnt end. A man on 

 the battlements of a distant tower, serves by comparison to 

 measure at once its magnitude and its distance — a full grown 

 oak, the elevation and extent of the hill on which it flourishes. 

 For a long period, the remotest mountains in the prospect 

 are regarded by the child as the boundary of the world. His 

 field of vision then extends to the terrestrial horizon.- A solid 

 vault of blue, studded with diminutive stars, appears to rest 

 on the flat earth as on a foundation ; and many a year has he 

 numbered before his encreasing knowledge countervails the 

 habit of his perceptions, and lends his imagination wings to 

 rise tlirough a yielding firmament, and discover through a 

 vista extending millions of miles, innumerable suns which he 

 had been taught to call stars, millions of miles in circum- 

 ference, and multiplied millions asunder : while Reason and 

 Fancy unite with Philosophy in peopling the invisible void 

 with systems of habitable orbs, as infinite in number as the 

 suns round which they revolve. 



Thus instructed by the most confined and local of the 

 senses, the most unrestricted and expansive becomes per- 

 •fect. And a circle scarcely one-tenth of an inch in diameter, 

 . whose sphere of vision is at first not more extensive than that 

 circle, in the progress of time acquires, by force of habit, 

 the astonishing power of comprehending within its diminu- 

 tive sphere the stupendous universe. 



