June io, 1920] 



NATURE 



447 



is never that which can be present all at once, 

 but that which is being- realised in the totality of 

 phases throug-h which the existent thing* in 

 -question passes. 



Since the appearance of his well-known paper 

 in the Phil. Trans, of. 1906, Prof. Whitehead has 

 been wrestling with the problem which considera- 

 tions such as these occasion, and he has now 

 worked out a positive theory of the structure and 

 di\ersification of Nature, upon the basis of which 

 a rationale can be furnished of the concepts indis- 

 pensable in mathematical physics. The aim, then, 

 of the present volumt^'iriay be said to be twofold : 

 (i) To determine by analysis of what is offered in 

 perceptual experience the ultimate data of science 

 and their relations ; and (2) to show how the 

 ':ncepts of mathematical physics and their 

 rlations can be exhibited as functions of the 

 former. 



Nature, so I understand Prof. Whitehead to 

 mean, must be regarded as in its totality a con- 

 tinuous stream of process, of becoming, of 

 creative advance. Within this whole there call to 

 be distinguished two essentially different, yet 

 intimately connected, types of entity — events and 

 •objects. Employing, again, Aristotelian phrase- 

 ology (and in many ways Prof. Whitehead's 

 scheme of Nature more nearly resembles the Aris- 

 totelian scheme than any other), events constitute 

 the vA.77 and objects the eiSos of things. Events 

 are either durations or bits of a duration, and a 

 "duration" is a "slab of Nature," limited tem- 

 porally, but unlimited spatially, which is con- 

 temporaneous with the specious present of any 

 percipient. The fundamental relation of events 

 is that of extending over each other, and this 

 relation of "extending over" is the common root 

 from which both temporal extension and spatial 

 ■extension take their orig-in. Strictly speaking-, 

 events themselves do not change ; they pass into 

 other events, and in passing- become parts of 

 larger events, the passage of events being exten- 

 •sion in the making-. Moreover, some of the 

 events that are parts of durations (e.g. a specific 

 state of perceiving) have a relation of cogredience 

 to a certain duration — that is to say, they are 

 temporally coextensive with it. and they occupy 

 in it a fixed spatial position. Furthermore, events 

 are the " situations " of objects — an object is 

 located in an event as that event's characteristic 

 or quality. Like Aristotle's e'So?, an object is 

 permanent. When we speak of its change we 

 really mean its diverse relationships to diverse 

 events. Precisely the same object can characterise 

 two or more events. The continuity of Nature is 

 to be found in events. The atomic properties of 

 Nature reside in objects. There is, in short, a 

 NO. 2641, VOL. 105] 



structure of events (an " ether of events " rather 

 than a material ether), and it provides the frame- 

 work of the externality of Nature within which 

 objects have their subsistence. This structure is 

 capable of being analysed in a number of different 

 ways, and by adopting different modes of analysis 

 we human beings can g^et at the various kinds of 

 events which are " situations " of different types 

 of objects. The more important of these types 

 are: (a) Sense-objects— e.^. definite sense-data; 

 (h) perceptual objects — i.e. the so-called "things" 

 of ordinary experience ; and (c) scientific objects — 

 i.e. the characteristics (electrons, etc.) of events 

 as active conditions. W'ith the exception of those 

 perceptual objects that are delusive, all these types 

 of objects are equally real. Their esse is neither 

 percipi nor intellegi. 



For the mathematician the detailed working out 

 of the way in which the concepts of point, instant, 

 particle, etc., may be brought into connection with 

 the data just indicated will probably be the most 

 valuable part of the treatise ; but I must be con- 

 tent to record that it is accomplished throug^h 

 persistent applications of what is named the 

 method of extensive abstraction. This method, 

 it is explained, is that which in its own sphere 

 (the sphere, namely, of geometry and mechanics) 

 follows the procedure of the differential calculus 

 in the region of numerical calculation. It converts 

 a process of approximation into an instrument of 

 exact thought. By its means, as Dr. Broad has 

 neatlv expressed it, the convenience in these 

 concepts is retained, while the fiction in them is 

 eliminated. 



With the main principles of Prof. Whitehead's 

 philosophy, yielding, as they do, a view of Nature 

 strikingly antithetical to that of the logical 

 atomism developed by Mr. Russell, the present 

 reviewer is in close agreement. One would like 

 to press, indeed, for a fuller elaboration of the 

 notions of "duration," "event," and "passage of 

 events " than is here attempted. For one has an 

 uneasy feeling that a host of embarrassing prob- 

 lems lies concealed in those notions. -Vnd then, 

 again, one is uncertain about the mode in which 

 events are supposed to be apprehended. While 

 objects are recognised, events, we are told, are 

 "lived through," by which apparently we 

 are to understand that not only the "per- 

 cipient event " {i.e. the actual phase of ex- 

 periencing), but also the whole duration with 

 which it is cogredient is "lived through." 

 Yet obviously it is not meant that the 

 countless other events, some cogredient and 

 others not with that duration, are in like 

 manner "lived through," and one fails to see 

 how there fan be any unique process of appre- 



