I want to know the answer to the following question:
What was the first time period that a significant change began to happen in Cubism?
All the background I'm provided with is that "Considerations manifested by Cubists prior to the outset of World War I—such as the fourth dimension, dynamism of modern life, the occult, and Henri Bergson's concept of duration—had now been vacated, replaced by a purely formal frame of reference.". Is that enough to answer the question?
Answer: no