Material world means step by step, simply danger. That is material world. So we have to find out pratikāram, counteraction, how to save yourself from danger. Just like when we walk, we see in so many doors, "Danger." So that you are warned. Sometimes the doors are: "Beware of the dog." So you have to take care, "No, I shall not enter." So everything there is danger, and there is pratikāram, counter, counteraction, how to save yourself from it. This is called struggle for existence.