Letter from Thomas Gold to Dr Alar Toomre, Department for Mathemtics, Massachusetts Institute of Technology, Cambridge, Massachusetts Thanks him for the reprint. Indeed he does persuade Gold, and he is pleasantly surprised that it has been possible to solve the problem of the origin of thin extensions of galaxies. Does not often acknowledge his intuition in pysics has bben wrong, but this is clearly a case in point. 13 March 1973