"... in programming there is a widespread first order theory that one shouldn't build one's own tools, languages, and especially operating systems. This is true --- an incredible amount of time and energy has gone down these ratholes. On the second hand, if you can build your own tools, languages, and operating systems you absolutely should because the leverage that can be obtained (and often the time not wasted in trying to fix other people's not quite right tools) can be incredible."
- Alan Kay, in http://www.vpri.org/pdf/m2004001_power.pdf