# Quote — Henri Poincaré, The Value of Science

> 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. ...[C]auses which have produced a certain effect will never be reproduced except approximately.

- Author: [Henri Poincaré](https://www.leafyquotes.com/henri-poincare.md)
- Book: [The Value of Science](https://www.leafyquotes.com/henri-poincare/the-value-of-science.md)
- Source: [Wikiquote](https://en.wikiquote.org/wiki/Henri_Poincar%C3%A9#Ch._2:_The_Measure_of_Time) ([CC BY-SA 4.0](https://creativecommons.org/licenses/by-sa/4.0/))
- Topics: [science](https://www.leafyquotes.com/topics/science.md)
- Quote page: https://www.leafyquotes.com/henri-poincare/the-value-of-science/in-physical-reality

## More from this book

> Does the harmony the human intelligence thinks it discovers in nature exist outside of this intelligence? No, beyond doubt, a reality completely independent of the mind which conceives it, sees or feels it, is an impossibility. A world as exterior as that, even if it existed, would for us be forever inaccessible.

[Quote page](https://www.leafyquotes.com/henri-poincare/the-value-of-science/does-the-harmony.md)

> Time and Space … It is not nature which imposes them upon us, it is we who impose them upon nature because we find them convenient.

[Quote page](https://www.leafyquotes.com/henri-poincare/the-value-of-science/time-and-space.md)

> The advance of science is not comparable to the changes of a city, where old edifices are pitilessly torn down to give place to new, but to the continuous evolution of zoologic types which develop ceaselessly and end by becoming unrecognizable to the common sight, but where an expert eye finds always traces of the prior work of the centuries past. One must not think then that the old-fashioned theories have been sterile or vain.

[Quote page](https://www.leafyquotes.com/henri-poincare/the-value-of-science/the-advance-of-science.md)