4 INTRODUCTION TO 



Therefore, to make up the loss as much as possible, it is incumbent 

 on us to go as far back as our knowledge directs us ; to compare those 

 [states of things] with great care and accuracy with the present ; and 

 to mark down what state things are now iu ; [in order] that future 

 ages may be able to account for what we are now ignorant of. For, 

 by their being acquainted with what has happened within the History 

 of Natural Things, the state that things were in prior to such in- 

 quiries — those changes prior to the present — may be hereafter toler- 

 ably well accounted for. 



To attempt to trace any natural production to its origin, or its first 

 production, is ridiculous ; for it goes back to that period, if ever such 

 existed, of which we can form no idea, viz. the beginning of time. 

 But, I think, we have reason to suppose there was a period in time in 

 which every species of natural production was the same ; there then 

 being no variety in any species ; but the variations taking place on the 

 siu'face of the earth, such as the earth and water changing situations, 

 which is obvious ; as also the change in the poles or ecliptic, which 

 I think is also obvious. The varieties [so produced] are but few and 

 are still existing in what may be called the ' Natural ' Animal. Also 

 civilization has made varieties in many species, and without number, 

 which are the 'Domesticated.' 



In the study of any science, the principles of which are not univer- 

 sally known or understood, it becomes not only necessary to teach the 

 science itself or what its principles are, but it is always necessary to 

 say what it is not ; for, from a want of a sufficient knowledge of the 

 subject, many sciences have been blended with one another so as to 

 unite them where they had no connexions, and thus [they have been] 

 falsely made to appear to belong to each other : by which means it was 

 difficult to say where one principle began and another ended, or that 

 there was any one principle inseparable from another. 



The most familiar or most known is commonly used to explain the 

 most unintelligible. Thus, for instance, Mechanics were introduced to 

 explain the effects produced by Chemistry, and both Mechanics and 

 Chemistry (which last was partly explained by Mechanics) have been 

 introduced as the cause of many of the operations both of the Vegetable 

 and Animal productions, in which they have not the least share. 



In the Natural History of Vegetables and Animals, therefore, it will 

 be necessary to go back to the first or common matter of this globe, 

 and give its general properties ; then see how far these properties are 

 introduced into the vegetable and animal operations ; or rather, perhaps, 

 how far they are of use or subservient to their actions. 



All matters, of whatever kind, have properties common to them all, 



