How can material senses perceive something spiritual?

In one of your posts, you mentioned that God is Nirguna in the sense that he has no material qualities. The color blue as we perceive it corresponds to a specific wavelength range (around 400-500 nm). Any material object is blue because it reflects these wavelengths. Sri Krishna’s color is described as blue. When He was present on earth in His spiritual form, the devotees saw him with their material eyes and saw Him as blue. But as His qualities are spiritual, His color should also be spiritual. Then, is it that His spiritual color interacts with the material senses and causes the sensation of blue and so we call Him blue, but in actuality we cannot perceive His true (spiritual) color? Similarly, one could ask about His form. When the eyes of the soldiers on Kurukshetra were seeing Sri Krishna, they were seeing the spiritual form, yet they had a sensation of His form sitting on the chariot, moving His hands while controlling the horses etc. How does the spiritual get perceived by the material? In BG chapter 11, Arjuna needed spiritual eyes to see Sri Krishna’s Vishwarupa. Was there a similar requirement for the general masses of people to see Sri Krishna’s form?