Standard CL Library: where is it?

I've been pretty busy lately, but surely I am slowly creeping along with my desire to finally learn some CL. I am half way through Seibel book, I have tons of bookmarks to Cliki, my emacs skills got better... But the giant, enormous question, Question #1 that I was patiently waiting for the answer for, remains unanswered: where is the standard Common Lisp Library? You know, like clib for C or Ruby Core, or Python's famous lib? Sure there are some functions that all CLs implement, but where are they listed? Where is the "missing manual"? Seibel's pulling stuff out of his hat all the time. Even Wikipedia article about Common Lisp says: "The Common Lisp library relies heavily on such higher-order functions." What library are they talking about? Where is it documented?