I think it was priests and nobles because before the printing press was invented they made written copies of the bible.
Blue and yellow mixed together makes green more blue than yellow make more of a teal
The most important limitation of stone is the lack of tensile strength, the capacity of a material to withstand binding.
Stone is durable and impressive stuff, but it's also challenging to quarry, and heavy to move, and it has tension and stress limitations. Where there are resources available to excavate and cut it precisely, stone can be an extremely strong and useful natural material. Unlike brick, it can be stacked without mortar and support heavy vertical loads. Stone resists deforming, weathers the elements well, withstands fire and helps maintain stable interior environments.
