MIND AS A MEASURE OF NATURE. 687 



laws of thought. No psychological theory has greater probability 

 than that which bases the units of knowledge in experience. Since 

 the time of Locke and Hume, the drift of speculation has been steadily 

 in the direction of a more or less modified empiricism. The more far- 

 sighted of the intuitionists cast aside everything they thought could 

 embarrass their theory, and were content to allow that the matter of 

 thought was based upon experience, while reserving as the province of 

 intuition the mental forms by which knowledge was possible. The 

 theory of evolution explains this intuitional residue by extending the 

 experience of the individual to the experience of the race, and showing 

 that what may be intuitive (in every sense, except the supernatural, in 

 which that word was formerly used) to the individual is so in conse- 

 quence of inherited tendencies corresponding to the aggregate experi- 

 ence of his ancestors. 



But we do not need to urge mental theories, however probable, to 

 show that our knowledge of the universe is dependent upon our sur- 

 roundings. A little difference in the physical condition of the earth 

 would have sufficed to have utterly changed our conception of nature. 

 Make the not very inconceivable supposition that our earth bore the 

 same relation to the sun that the moon does to the earth rotating 

 once on its own axis to each revolution about the sun, and remaining 

 nearly perpendicular to the ecliptic, thus always presenting the same 

 side to the sun's rays how would it have aifected our knowledge of 

 nature ? To what modest proportions would not only science have 

 shrunk, but also our mental or intuitive conceptions of nature ! 



Astronomy has been well called the mother of the sciences. The 

 apparent motions of the sun, moon, and stars through the heavens, and 

 the motions of the planets among the stars, contributed to produce a 

 wonder in the minds of the beholders that might well cause astronomy 

 to be the first studied of the sciences. In our hypothetical world, the 

 sun would appear stationary in the heavens, more or less removed from 

 the zenith according to the position of the observer. On the center of 

 the earth's surface would be a torrid zone upon w^hich the vertical rays 

 of the sun would pour down with unremitting severity, with no alter- 

 nation of day and night to temper its influence. Outside of this would 

 be a temperate zone well adapted, it might be, to the existence of 

 human beings, but having no change of seasons, only one monotonous 

 summer day, varying in temperature according to location. The tem- 

 perate zone would gradually give place to a frigid zone, and, as the 

 day darkened into an eternal night, this would be succeeded by an 

 impenetrable region in which the degree of cold would vastly exceed 

 anything we have on earth at present. Thus man, confined to some- 

 what less than half the globe, would see nothing of the moon or stars, 

 and the earth, with the sun shining on it, would be the only bodies 

 visible. There would be no natural divisions of time into days, weeks, 

 months, or years. Mathematicians might calculate the hemispherical 



