'A teacher's questioning must use reason to explore the root of truths ... quoting naked authority will declare a thing certain but give no shred of understanding of how it is true, sending students away empty-headed' Thomas Aquinas Aquinas was a thirteenth-century university teacher educating students in an ecclesiastical tradition, but because he thought authority without reason could not make sense of truth he taught his students how to question. Timothy McDermott examines some of Aquinas'squestions and asks whether they can make sense of the truths the twenty-first century takes for granted. He considers the role of regularity and chance in the natural world, mind and matter, freedom and moral obligation, law and society, suffering and evil, hope and hopelessness, and what place can rationally be given to Jesus Christ, to religion and churches, to faith and love and a God. Extracts are taken from the records of Aquinas's classroom disputations (Quaestiones Disputatae) and two brilliant conspectuses of his teaching: the Summa Contra Gentes, which attempted a reasoned dialogue with non-Christian (mainly Arabic) scholars, and the Summa Theologiae, which was addressed to his Christian students.