3.2 Why FunnelWeb Wasn't Used to Write Itself

After Knuth created the WEB literate preprocessing system, he re-wrote it using WEB and distributed the source code in WEB source form. To allow the WEB source code to be tangled by users not yet having a copy of WEB, he also included the tangled Pascal code for the Tangler.

While this approach is heroic and serves to convey a commitment and a confidence in literate programming, it seemed to me that writing FunnelWeb in FunnelWeb would simply be asking for trouble. For a start, it would be very hard to modify any feature of FunnelWeb that had been used to write FunnelWeb. Also, the thought of what would happen if the working executable became inoperative for some reason does not bear thinking upon.

One million billion computer programs were written in the non-literate style before FunnelWeb was created. Why not one more?