l8 HISTORY OF ASTRONOMY.

eafily along them, without effort and withoutinterruption. They fall in with the natural careerof die imagination ; and as the ideas which repre-sented fuch a train of things would feem all mu-tually to introduce each other, every lall thoughtto be called up lay the foregoing, and to call upthe succeeding; fo when the objects themfelvesoccur, every laft event feems, in the fame man-ner, to be introduced by the foregoing, and tointroduce the iueceeding. There is no break, noflop, no gap, no interval. The ideas excited byfo coherent a chain of things f'ecm , as it were, tofloat through the mind of their own accord, with-out obliging it to exert itfelf, or to make anyeffort in order to pafs from one of them to an-other.

Butifthis cuftomary connexion be interrupted,if one or more objects appear in an order quitedifferent from that to which the imagination hasbeen accuftomed, and for which it is prepared,the contrary of all this happens. We are at firftfurprifed by the unexpeclednefs of the new appear-ance, and when that momentary emotion is over,we ftill wonder how it came to occur in thatplace. The imagination no longer feels the ufualfacility of palling from the event which goes be-fore to that which comes after. It is an order orlaw of fucceflion to which it has not been accus-tomed, and which it therefore finds fome difficul-ty in following, or in attending to. The fancyis flopped and interrupted in that natural move-ment or career, according to which it was