Optique géométrique : Cours et exercices corrigés

“ Sorrow prepares you for joy. It violently sweeps everything out of your house, so that new joy can find space to enter. It shakes the yellow leaves from the bough of your heart, so that fresh, green leaves can grow in their place. It pulls up the rotten roots, so that new roots hidden beneath have room to grow. Whatever sorrow shakes from your heart, far better things will take their place. ” ― Rumi