An apostolic exhortation on the call to holiness in today's world, offered not as a treatise but as a way of reproposing the universal call to holiness in a practical key. Its five chapters treat the saints next door and holiness lived in ordinary circumstances; two subtle enemies of holiness, the contemporary forms of gnosticism and pelagianism; the Beatitudes and Matthew 25 as the great criterion of a holy life; five marks of holiness in the modern world — perseverance, joy, boldness, community and constant prayer; and the necessity of spiritual combat, vigilance and discernment.