Getting the first version of TeX to work, I… I also had to… to get the fonts ready – the… the letter forms – and after... after 5 months I… I had something I could finally test.  And I… but after… after 2 days I realized why my students hadn't gotten any further than they did, because… because I had to keep changing the language constantly, every… several times an hour as I was… as I was beginning to write the… the code.  And if the students… if the… several of my friends have tried to… to direct software projects where they set the specifications and they say to the students, write the… write the code… and it never works.  And now I know why, because the students would have to schedule an appointment... every few minutes they have the students working on it, they have to schedule an appointment with the professor to… to discuss what… what the issue is.  And then the professor would have to, you know, take 15 minutes to get in the frame of mind to understand what the problem is, or he'll say, ‘Oh yes, do this’, and then the student can go back and work for another 5 minutes before another question comes up. So it just takes forever. When you do enough… working on a first generation software like this I think it has to be done… the designer and the implementer have to be the same person.