The speaker relates philosophy to and distinguishes it from all the arts and sciences in terms of its breadth and depth. Philosophy thinks about things, and thoughts, and words and actions (“words and deeds”, in Cicero’s phrase). There are examples of philosophers who have reduced all three of them to one and of philosophers who have kept them distinct. There have been revolutions in philosophy, responsive to great changes in cultural life, in science and politics, and in reaction against established traditions within philosophy. In modern times, there has been a metaphysical revolution against the Aristotelian schoolmen, an epistemological revolution against that metaphysical tradition, and a revolution of phenomenology, logic, and pragmatism against the psychologism of that epistemological tradition. The last part of the lecture considers important ideas of that last revolution that have become determinant of the ways in which we think about science and life. The goal of the lecture was to show the usefulness of philosophy in the past and to promote liberation of thinking for new gains in the future.