“…If the mind imposes its own subjective forms on nature, then the nature it knows cannot be a realm of things as they are in themselves; it must be merely a realm of things as they appear to us. In short, our knowledge must be limited to appearances; reality is forever obscured from our view. Hence metaphysics, the “science of reality,” must be an empty discipline, a mere pretension and illusion to be refuted rather than encouraged.
Thus Kant’s philosophy is at one and the same time optimistic and pessimistic. He reassures us that our mathematics and science is valid knowledge, but he cautions us that it is valid only for appearances, not for reality itself. In the end, the transcendental philosophy is a lesson in intellectual humility, for it teaches us that the human mind lacks the power to penetrate the veil of appearance and grasp the inner nature of independent reality.”
—————————
Thanks for reading
Ibrahim El Merehbi 
Here is an interesting question: if (according to Kant) time and space are only forms of our knowledge (not existing by themselves), why are the physicists saying that space is curved and time is relative? Are time and space physical entities? Aren't they confusing time and space with the metric of time and space? Can I say the space is curved because my ruler is curved? Or, can I say the time is relative because my watch is mad?
LikeLike
Thanks for your deep comment. These are very good questions.Well here's my quick reply:Einstein's relativity, more precisely his field equations [1], are what “mathematically prove” that space is curved due to matter & energy & according to his special relativity that not just time but measurements are relative. Moreover, physical experiments have indeed shown that space is curved (this is Einstein's explanation of what gravity is which Newton couldn't explain!) and that time slows down as you speed up (of course this is not noticeable with our speeds).As for the space time confusion; what Einstein did was merge the three spatial & the 1 time dimension into a 4-vector space [2]In the end of your comment (the ruler idea) is somehow true; I'd say that the physicists' & mathematicians' ruler is “logic” and logic is a “mind product”. I often like to ask my self: what if the logic we base all our science and decisions on is not absolute?![1] https://en.wikipedia.org/wiki/Einstein_field_equation%5B2%5D https://en.wikipedia.org/wiki/Four-vector
LikeLike