“The whole is other than the sum of the parts”
— Kurt Koffka
This is the correct version of the sentence that is usually referred in english as “The whole is more than the sum of the parts”. Once I was pointed out to the right one by Corrado, it immediately rang true to me, even before the explanation:
“This is not a principle of addition”
Which is absolutely correct. I however understand the reason why “more” got popular in place of “other”: it’s clearer that we are getting out something on top, something beyond the basic stimulus, while “other” requires a deeper understanding of the perceptual dynamics of gestalt psychology, which for a sentence repeated in isolation, isn’t often the case.