Most recently for me, I saw Arthur&#x27;s code which might not be what you&#x27;re looking for. The origins of J[1], is publicly available C code, and even if it doesn&#x27;t move you, consider spending some time on it anyway.<p>When I was younger, I learned a lot from reading djb&#x27;s code[2] changed the way I think about application design and [3] changed my mind about system administration. Actually everything djb wrote is worth learning from.<p>Before that I recall specifically sicp[4] giving me a lot to think about.<p>There are also bigger things (like plan9[5] and emacs[6]) that I&#x27;ve found interesting.<p>[1]: <a href="http:&#x2F;&#x2F;nsl.com&#x2F;papers&#x2F;origins.htm" rel="nofollow">http:&#x2F;&#x2F;nsl.com&#x2F;papers&#x2F;origins.htm</a><p>[2]: <a href="http:&#x2F;&#x2F;cr.yp.to&#x2F;djbdns.html" rel="nofollow">http:&#x2F;&#x2F;cr.yp.to&#x2F;djbdns.html</a><p>[3]: <a href="http:&#x2F;&#x2F;cr.yp.to&#x2F;daemontools.html" rel="nofollow">http:&#x2F;&#x2F;cr.yp.to&#x2F;daemontools.html</a><p>[4]: <a href="https:&#x2F;&#x2F;mitpress.mit.edu&#x2F;sicp&#x2F;" rel="nofollow">https:&#x2F;&#x2F;mitpress.mit.edu&#x2F;sicp&#x2F;</a><p>[5]: <a href="http:&#x2F;&#x2F;9p.io&#x2F;plan9&#x2F;index.html" rel="nofollow">http:&#x2F;&#x2F;9p.io&#x2F;plan9&#x2F;index.html</a><p>[6]: <a href="http:&#x2F;&#x2F;www.gnu.org&#x2F;software&#x2F;emacs&#x2F;" rel="nofollow">http:&#x2F;&#x2F;www.gnu.org&#x2F;software&#x2F;emacs&#x2F;</a>