Most notably, it says here it began in the lower classes and percolated up to the higher classes.

最值得注意的是，这里说的是从下层阶级开始，一直渗透到较高的阶层。

Red giants are fantastically bright because of all the energy percolating up from their interiors, coupled with their enormous size.

红巨星极其明亮，这是因为所有的能量都从它们的内部渗透出来，且其体积巨大。