There are two parties to every observation - the observed and the observer.


Space, Time and Gravitation, Chapter II (p. 30), At the University Press. 1921


There are two parties to every observation - the observed and the observer.

There are two parties to every observation - the observed and the observer.

There are two parties to every observation - the observed and the observer.

There are two parties to every observation - the observed and the observer.