The bit about the small forge forging a forge is skewering the Gentoo concept of toolchain bootstrapping.

Problem: how can you claim to have compiled the entire system on your own local machine if you need a compiler to compile a compiler? Where do you get that compiler from?

Solution: Use an external compiler to compile a compiler. Then use that compiler that you just compiled to compile itself again. Then use that second compiler to recompile the rest of the system.