‘Are you a priest?’ The question came from a taxi-driver in Mexico City’s Calle Francisco Madero. And it was, I suppose, a reasonable question. In Mexico, priests are never allowed in the street in robes, except at Easter time. I did once see a monk in habit walking at dusk between the churches of Santo Domingo and Caridad in San Cristobal de las Casas, but I was assured that he must have been a ghost. In addition, I now look, at a distance, vigilant and sombre: and that day there had been a great manifestacion of loyal Catholics a short distance away in the cathedral square, the Zocalo. The issue had assumed astonishing proportions. About three weeks before, the Museum of Modern Art had allowed a modern painter to exhibit in the main hall a representation of Our Lady of Guadalupe with the face of Marilyn Monroe in place of that of Our Lady. This blasphemy had outraged the leaders of Catholic opinion. The unwritten understanding in Mexico is that while the Church is not constitutionally recognised, the state does nothing to interfere with el culto. In a few weeks the director of the Museum of Modern Art resigned and began writing articles in the press about the unworthy prolongation of Mexico’s centuries of censorship. The assembly in the Zocalo followed. The previous day our host at a beautiful hacienda near the pyramids of Teotihuacan had said that he was returning to the capital on Saturday night, not Sunday, breaking the habit of a lifetime, in order to be present at the Zocalo at 8.30 a.m. He was taking the event exceptionally seriously.