When you have written 45 thick tomes in 29 years (1893-1922), along with winning the odd revolution, at least three things may happen: 1) you write yourself to death (Lenin at 52); 2) you repeat yourself every now and then; 3) you range over all sorts of odd stuff. In this case proof-reading, in response to Plekhanov:
In the original there was no comma after the word “other”. Unpretentious proof-readers usually correct such mistakes without making a fuss about it. Pretentious proof-readers write a feuilleton nearly half a column long about it!
Collected Works, vol 10, p. 460.