DEFINITIONS OF LIFE. 37 



ing phenomena as involved in, proceeding from, and so far 

 therefore explained by, the supposition of its progressive 

 intensity and of the gradual enlargement of its sphere, 

 the necessity of which again must be contained in the 

 idea of the tendency itself. In other words, the tendency 

 having been given in kind, it is required to render the 

 phenomena intelligible as its different degrees and modi- 

 fications. Still more perfect will the explanation be, should 

 the necessity of this progression and of these ascending 

 gradations be contained in the assumed idea of life, as 

 thus defined by the general form and common purport of 

 all its various tendencies. This done, we have only to 

 add the conditions common to all its phenomena, and those 

 appropriate to each place and rank, in the scale of ascent, 

 and then proceed to determine the primary and consti- 

 tutive forms, i. e. the elementary powers in which this 

 tendency realizes itself under different degrees and con- 

 ditions. 1 



1 The object I have proposed to myself, and wherein its distinction exists, 

 may be thus illustrated. A complex machine is presented to the common 

 view, the moving power of which is hidden. Of those who are studying 

 and examining it, one man fixes his attention on some one application of that 

 power, on certain effects produced by that particular application, and on a 

 certain part of the structure evidently appropriated to the production of these 

 effects, neither the one or other of which he had discovered in a neighbouring 

 machine, which he at the same time asserts to be quite distinct from the 

 former, and to be moved by a power altogether different, though many of the 

 works and operations are, he admits, common to both machines. In this sup- 

 posed peculiarity he places the essential character of the former machine, and 

 defines it by the presence of that which is, or which he supposes to be, absent 

 in the latter. Supposing that a stranger to both were about to visit the two 

 machines, this peculiarity would be so far useful as that it might enable him 

 to distinguish the one from the other, and thus to look in the proper place for 

 whatever else he had heard remarkable concerning either ; not that he or his 

 informant would understand the machine any better or otherwise, than tic 



