Pius XI was also a very demanding individual, certainly one of the stricter pontiffs at that time. He held very high standards and did not tolerate any sort of behaviour that was not up to that standard. In regard to Angelo Roncalli, the future Pope John XXIII, a diplomatic blunder in Bulgaria, where Roncalli was stationed, led Pius XI to make Roncalli kneel for 45 minutes as a punishment. However, when in due course Pius learnt that Roncalli had made the error in circumstances for which he could not fairly be considered culpable, he apologized to him. Aware of the implied impropriety of a Supreme Pontiff's going back on a reprimand in a matter concerning Catholic faith and morals, but also deeply conscious that on a human level he had failed to keep his temper in check, he made his apology "as Achille Ratti" and in doing so stretched out his hand in friendship to Monsignor Roncalli.