Have we really the right to speak of the cause of a phenomenon?

It is the sidereal day, that is, the duration of the rotation of the earth, which is the constant unit of time. ...However ...many astronomers ...think that the tides act as a check on our globe, and that the rotation of the earth is becoming slower and slower. Thus would be explained the apparent acceleration of the motion of the moon...

What postulate do we implicitly admit? It is that the duration of two identical phenomena is the same; or... that the same causes take the same time to produce the same effects. ...Is it impossible that experiment may some day contradict our postulate?

In physical reality one cause does not produce a given effect, but a multitude of distinct causes contribute to produce it, without our having any means of discriminating the part of each of them. ...Causes which have produced a certain effect will never be reproduced except approximately.

We should say: 'Causes almost identical take almost the same time to produce almost the same effects.'

Astronomers... define duration in the following way: time... so defined that Newton's law and that of vis viva [or of the conservation of energy] may be verified. Newton's law is an experimental truth... only approximate... We still have only a definition by approximation.

If... it be supposed that another way of measuring time is adopted... enunciation of the law would be... translated into another language... much less simple. So that the definition implicitly adopted by the astronomers may be summed up..: Time should be so defined that the equations of mechanics may be as simple as possible... [i.e.,] there is not one way of measuring time more true... only more convenient.

We should like to represent... the... universe, and... feel... we understood it. We... never can attain this representation: our weakness is too great. But... we desire... to conceive an infinite intelligence... which should see all, and... classify all in its time, as we classify, in our time, the little we see. ...This supreme intelligence would be only a demigod; infinite in one sense... limited in another, since it would have... imperfect recollection of the past... otherwise all recollections would be equally present... and for it there would be no time.

Yet when we speak of time... do we not unconsciously adopt this hypothesis... and put ourselves in the place of this imperfect god... Do not even the atheists put themselves in the place where god would be..?

This shows, perhaps, why we have tried to put all physical phenomena into the same frame. But that can not pass for a definition of simultaneity, since this hypothetical intelligence, even if it existed, would be for us impenetrable. It is... necessary to seek something else.

Is not my present nearer my past of yesterday than the present of Sirius?

Behold... the only... rule we can follow: when a phenomenon appears... as the cause of another, we regard it as anterior. ...Therefore by cause... we define time; but...how do we recognize which is the cause and which the effect? We assume... the anterior fact, the antecedent, is the cause of the... consequent. It is then by time that we define cause. ...Shall we escape from this vicious circle?

Sociology is the science which has the most methods and the least results.