Ernst Mach

From: Die Mechanik in ihrer Entwickelung (5th ed., 1904)
"Even in the simplest case, in which apparently we deal with the mutual action between only two particles, it is impossible to disregard the rest of the universe. Nature does not begin with elements, as we are forced to do. Certainly it is fortunate for us that we can sometimes turn away from the overwhelming all, and allow ourselves to study isolated facts. But we must not forget ultimately to amend and complete our views by taking into account what had been omitted."