Yay, it can add. No, I have no idea what the menorah's about, other than it's the CLISP logo. Maybe it's a reference to Lisp being the One True Language or something.
Unfortunately the adding is about all the Lisp I know—I'm learning it for my proglang class. The good thing about that is I can read Paul Graham articles and claim it's research:
You're most likely to get good design if the intended users include the designer himself. When you design something for a group that doesn't include you, it tends to be for people you consider to be less sophisticated than you, not more sophisticated.
That's a problem, because looking down on the user, however benevolently, seems inevitably to corrupt the designer. I suspect that very few housing projects in the US were designed by architects who expected to live in them. You can see the same thing in programming languages. C, Lisp, and Smalltalk were created for their own designers to use. Cobol, Ada, and Java, were created for other people to use.
If you think you're designing something for idiots, the odds are that you're not designing something good, even for idiots. —