[bullen]

I think you mean re-implement the wheel, people often misuse the term re-invent the wheel.

You actually need to change things for it to be called an invention:

http://move.rupy.se/file/wheel.jpg

That said I always write everything from scratch, to me it's the meaning of life;

If you are only using things you don't understand, you cannot (re-)invent anything.

Today we also do not own anything, which makes the problem even worse.

Rules for a good life: 1) own 2) understand 3) change!

[spfzero]

Feinman said something like that. IIRC, “I cannot understand it if I cannot create it.” I probably butchered it.

[bullen]

"What I cannot create, I do not understand" - What he meant by this was re-implement more than re-invent... re-invent is an oxymoron I just realized; you cannot re- something that needs to be new.