SKETCH OF BUY GENS. 839 



published till after the death of Huygens, was chiefly a treatise on 

 the habitability of other worlds than ours, aud was marked by curious 

 and ingenious speculations, of a character from which his other works 

 were almost entirely free. In this work, after expressing his belief in 

 the existence upon the planets of living bodies in no way inferior to 

 those on the earth, he added : " What obliges me to believe also that 

 there is a rational animal in the planets is that, if there is not, the earth 

 would have too great advantages (while it is one of the smallest of the 

 planets) and would be too much elevated in dignity (while it is neither 

 the nearest to the sun nor the most distant from it) over the other 

 planets, if it had an animal so much superior to all that they have. . . . 

 Finally, is it reasonable to suppose that the heavenly bodies among 

 which our earth occupies so modest a rank have been created only 

 in order that we other little men may enjoy their light and contem- 

 plate their situation and motion ?" He also gave some vivid pictures 

 of the scenery of the heavens as observed from the different planets, 

 paraphrases of which had wide circulation in an English work of popu- 

 lar astronomy of the last generation. In observing the moon he made 

 a study of its mountains and plains, and, remarking that the latter 

 were too rough to be lakes or oceans, concluded, what is now generally 

 believed, that the moon has no bodies of water ; also that it has no 

 atmosphere — none at least that rises above the valleys. 



At the beginning of the year 1695, Huygens lost his faculties — 

 an affliction he had suffered once before while residing in Paris, but 

 from which he had recovered after removal to his native land. This 

 time the affliction was permanent, except for a few lucid intervals 

 which he employed in making testamentary dispositions of his prop- 

 erty, and in consigning the care of his manuscripts to his friends Biir- 

 cher de Voider and Bernard Fullen. 



Like his illustrious contemporaries Descartes, Leibnitz, and Xewton, 

 Huygens was never married. He is described as having had a good 

 figure, and been possessed of a noble and elevated character. He was 

 affable and frank in his disposition, and gave a warm welcome to in- 

 quiring young men, whom he was always ready to direct in the way 

 of discovery. It was thus that Leibnitz came to him and received the 

 inspiration of which we have quoted the acknowledgment. Though 

 qualified by birth and fortune to shine in society, and constrained to 

 figure there for a part of his life, he preferred retreat, and passed all 

 of his time that he could in the country, immersed in his studies and 

 experiments. 



