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.If any event has the character of being an exhibition of the solar spectrumunder certain assigned circumstances, it will also have the character ofexhibiting dark lines in that spectrum.This long discussion brings us to the final conclusion that the concrete facts ofnature are events exhibiting a certain structure in their mutual relations andcertain characters of their own.The aim of science is to express the relationsbetween their characters in terms of the(168) mutual structural relations between the events thus characterised.Themutual structural relations between events are both spatial and temporal.If youthink of them as merely spatial you are omitting the temporal element, and if youthink of them as merely temporal you are omitting the spatial element.Thus whenyou think of space alone, or of time alone, you are dealing in abstractions,namely, you are leaving out an essential element in the life of nature as knownto you in the experience of your senses.Furthermore there are different ways ofmaking these abstractions which we think of as space and as time; and under somecircumstances we adopt one way and under other circumstances we adopt anotherway.Thus there is no paradox in holding that what we mean by space under one setof circumstances is not -what we mean by space under another set ofcircumstances.And equally what we mean by time under one set of circumstances isnot what we mean by time under another set of circumstances.By saying that spaceand time are abstractions, I do not mean that they do not express for us realfacts about nature.What I mean is that there are no spatial facts or temporalfacts apart from physical nature, namely that space and time are merely ways ofexpressing certain truths about the relations between events.Also that underdifferent circumstances there are different sets of truths about the universewhich are naturally presented to us as statements about space.In such a casewhat a being under the one set of circumstances means by space will be differentfrom that meant by a being under the other set of circumstances.Accordingly whenwe are comparing two observations made under different circumstances we have toask 'Do thePage 65Easy PDF Creator is professional software to create PDF.If you wish to remove this line, buy it now. Alfred North Whitehead - The Concept Of Nature.txt(169) two observers mean the same thing by space and the same thing by time?' Themodern theory of relativity has arisen because certain perplexities as to theconcordance of certain delicate observations such as the motion of the earththrough the ether, the perihelion of mercury, and the positions of the stars inthe neighbourhood of the sun, have been solved by reference to this purelyrelative significance of space and time.I want now to recall your attention to Cleopatra's Needle, which I have not yetdone with.As you are walking along the Embankment you suddenly look up and say,'Hullo, there's the Needle.' In other words, you recognise it.You cannotrecognise an event; because when it is gone, it is gone.You may observe anotherevent of analogous character, but the actual chunk of the life of nature isinseparable from its unique occurrence.But a character of an event can berecognised.We all know that if we go to the Embankment near Charing Cross weshall observe an event having the character which we recognise as Cleopatra'sNeedle.Things which we thus recognise I call objects.An object is situated inthose events or in that stream of events of which it expresses the character.There are many sorts of objects.For example, the colour green is an objectaccording to the above definition.It is the purpose of science to trace the lawswhich govern the appearance of objects in the various events in which they arefound to be situated.For this purpose we can mainly concentrate on two types ofobjects, which I will call material physical objects and scientific objects.Amaterial physical object is an ordinary bit of matter, Cleopatra's Needle forexample.This is a much more complicated type of object than a mere colour, suchas(170) the colour of the Needle.I call these simple objects, such as colours orsounds, sense-objects.An artist will train himself to attend more particularlyto sense-objects where the ordinary person attends normally to material objects.Thus if you were walking with an artist, when you said 'There's Cleopatra'sNeedle,' perhaps he simultaneously exclaimed 'There's a nice bit of colour.' Yetyou were both expressing your recognition of different component characters ofthe same event.But in science we have found out that when we know all about theadventures amid events of material physical objects and of scientific objects wehave most of the relevant information which will enable us to predict theconditions under which we shall perceive sense-objects in specific situations.For example, when we know that there is a blazing fire (i.e.material andscientific objects undergoing various exciting adventures amid events) andopposite to it a mirror (which is another material object) and the positions of aman's face and eyes gazing into the mirror, we know that he can perceive theredness of the flame situated in an event behind the mirror -- thus, to a largeextent, the appearance of sense-objects is conditioned by the adventures ofmaterial objects.The analysis of these adventures makes us aware of anothercharacter of events, namely their characters as fields of activity whichdetermine the subsequent events to which they will pass on the objects situatedin them.We express these fields of activity in terms of gravitational,electromagnetic, or chemical forces and attractions.But the exact expression ofthe, nature of these fields of activity forces us intellectually to acknowledge aless obvious type of objects as situated in events.I mean molecules(171) and electrons.These objects are not recognised in isolation
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