There are two kinds of beauty, one called tiferet, the other called hod:
Tiferet refers to beauty that we understand.
Hod refers to beauty that inspires awe, because understanding escapes us.
This itself is something of amazing beauty: That an idea can reach down and touch a mind that cannot understand it.
How is this possible? Because at the essence of all thought lies beauty and delight. Sometimes we grasp the beauty that we can understand. Sometimes we grasp the essence that cannot be understood.
Igrot Kodesh, vol. 2, p. 301.