Compact languages and libraries have the advantage that one person can understand most of an implementation. Two of the most elegant programming languages, Squeak Smalltalk and Ruby, have sufficiently compact implementations to understand, given some effort. And this effort is worthwhile - a lesson I learned in the 1970s when I worked as a systems programmer: I kept listings of key parts of the PrimeOS (Multics based) operating system and for the Lisp and FORTRAN implementations handy at home and in my office. Time spent reading through the code paid huge dividends whenever I had to do any systems level programming. Reading the code helps create a mental map of whatever software that you are using.
The implementation of Ruby and the standard Ruby libraries is compact, basically divided into the C implementation of Ruby itself and the Ruby code for the standard libraries. If you are going to be working much with Ruby then consider creating at least a project (using Eclipse, IntelliJ, TextMate, etc.) with the library source code. Good for library reference, looking up APIs, and for just reading code.
I would make the same suggestion to developers who use Squeak Smalltalk (or other implementations): you have the source code to the standard libraries: read it!
I also enjoy and am very productive using the Java and Common Lisp frameworks, but these languages with their standard libraries are so huge that I would personally never attempt to dive in and understand their implementations. Not having a mental road map of the implementations of Common Lisp and Java reduces the effectiveness of these platforms.