So acquire the habit of being present at this activity of the material and moral universe. Learn to look; compare what is before you with your familiar or secret ideas. Do not see in a town merely houses, but human life and history. Let a gallery or a museum show you something more than a collection of objects, let it show you schools of art and of life, conceptions of destiny and of nature, successive or varied tendencies of technique, of inspiration, of feeling. Let a workshop speak to you not only of iron and wood, but of man's estate, of work, of ancient and modern social economy, of class relationships. Let travel tell you of mankind; let scenery remind you of the great laws of the world; let the stars speak to you of measureless duration; let the pebbles on your path be to you the residue of the formation of the earth; let the sight of a family make you think of past generations; and let the least contact with your fellows throw light on the highest conception of man. If you cannot look thus, you will become, or be, a man of only commonplace mind. A thinker is like a filter, in which truths as they pass through leave their best substance behind.
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Thus the wise man, at all times and on every road, carries a mind ripe for acquisitions that ordinary folk neglect. The humblest occupation is for him a continuation of the loftiest; his formal calls are fortunate chances of investigation; his walks are voyages of discovery, what he hears and his silent answers are a dialogue that truth carries on with herself within him. Wherever he is, his inner universe is comparing itself with the other, his life with Life, his work with the incessant work of all beings; and as he comes forth from the narrow space in which his concentrated study is done, one gets the impression, not that he is leaving the true behind, but that he is throwing his door wide open so that the world may bring to him all the truth given out in its mighty activities.
— Antonin-Gilbert Sertillanges in The Intellectual Life (1921) translated from French by Mary Ryan