Christian hope is not mere optimism or a "positive attitude" toward the world but a vital link to eternal salvation, Pope Francis said. The Pope was speaking this morning during a morning Mass he celebrated in the Vatican guesthouse, where he lives. The congregation included a visiting group of Mexican priests celebrating the 25th anniversary of their ordinations. Referring to the day's reading from Paul's Letter to the Romans (8: 18-25), which deals with the theological virtue of hope, the Pope said that hope was harder to understand than the other two theological virtues - faith and charity - whose results are more evident to the senses. Early Christians represented hope as an anchor fixed on the shore of the hereafter, he said. "Where are we anchored, each of us?" Pope Francis asked. "Are we anchored right on the shore of that distant ocean or are we anchored in an artificial lake we have made, with our rules, our ways of behaving, our schedules, our clericalism, our ecclesiastical, not ecclesial, attitudes?" "It is one thing to live in hope, because in hope we are saved, and another thing to live as good Christians, nothing more," he said. The Pope drew on St Paul's use of childbirth as an image of hope, which he said involves waiting to give life. "When a woman gets pregnant, she is a woman, but she is never just a woman, she is a mamma. And hope is something like this. It changes one's attitude. We are ourselves, but we are not ourselves. We are ourselves, seeking what is over there, anchored over there."