I read Shaw's toast to Einstein probably a good 50 years ago or more, but lacking a reference as well as the appropriate memory, I was not certain where to find a certain passage I remembered. Now I have located the text of the whole speech:
Toast to Albert Einstein, by Bernard Shaw, edited by Fred D. Crawford, Shaw, Vol. 15 (1995), pp. 231-241.
This is more or less the passage I remembered:
As an Englishman, Newton was able to combine mental power so extraordinary that if I were speaking fifty years ago, as I am old enough to have done, I should have said that his was the greatest mind that any man had ever been endowed with. And he contrived to combine the exercise of that wonderful mind with credulity, with superstition, with delusion which would not have imposed on a moderately intelligent rabbit. (Laughter)
As an Englishman also, he knew his people, he knew his language, he knew his own soul. And knowing that language, he knew that an honest thing was a square thing; an honest bargain was a square deal; an honest man was a square man, who acted on the square. That is to say, the universe that he created had above everything to be a rectilinear universe. (Laughter)
Now, see the dilemma in which this placed Newton. universe; He knew his universe, he knew that it consisted of heavenly bodies all in motion; and he also knew that the one thing that you cannot do to any body in motion whatsoever is to make it move in a straight line. You may fire it out of a cannon with the strongest charge that you can put into it. You may have the cannon contrived to have, as they say, the flattest trajectory that a cannon can have. It is no use. The projectile will not go in a straight line. If you take a poor man - the poorer the better - if you blindfold that man, and if you say, "I will give you a thousand pounds if you, blindfolded, will walk a thousand yards in a straight line," he will do his best for the sake of the thousand pounds to walk in a straight line, but he will walk in an elliptical orbit and come back to exactly the same place.
Now, what was Newton to do? How was he to make the universe English? (Laughter) Well, mere facts will never daunt an Englishman. They never have stopped one yet, and they did not stop Newton. Newton invented - invented, mind you; some people would say discovered, I advisedly say he invented - a force, which would make the straight line, take the straight lines of his universe and bend them. And that was the force of gravitation. And when he had invented this force, he had created a universe which was wonderful and consistent in itself, and which was thoroughly British. (Laughter)
I remembered the association of cultural and physical rectilinearity, and I also remembered that Shaw failed to understand the nature of scientific idealization and physical explanation. Perhaps by this time I was aware of Shaw's penchant for the crackpot mysticism that vitiated his rational diagnosis of society's flaws.
However, I have just learned that Shaw's anti-science was more extensive and preposterous, but was mitigated somewhat, partially due to his friendship with Einstein:
Shaw, Einstein and Physics, by Desmond J. McRory, Shaw, Vol. 6 (1986), pp. 33-67.
Shaw's animosity towards (astro)physics was mitigated and in any case overshadowed by his persistent contempt for biology. Einstein's relativity (and to a lesser extent quantum mechanics) shows up in many of Shaw's later works. Einstein is likened to a great artist. The revolution in physics is favorably contrasted with what came before.