Different winds come from all directions. Some are clear, some carry dust, some are cold or hot, fierce gales or gentle breezes. In the same way sensations arise in the body–pleasant or unpleasant or neutral. When a meditator sees sensations as he does the winds, coming and going, clear or dust laden, fierce or gentle, he will fully understand them and be free from dependence on them. When he understands sensations perfectly, he will see beyond this conditioned world.
-Samyutta Nikaya