Seneca · On the healing power of the mind
Letters 78.7
Let us now return to the consideration of the characteristic disadvantage of disease: it is accompanied by great suffering. The suffering, however, is rendered endurable by interruptions; for the strain of extreme pain must come to an end. No man can suffer both severely and for a long time; Nature, who loves us most tenderly, has so constituted us as to make pain either endurable or short.
Seneca, Letters to Lucilius 78.7, translated by Richard Mott Gummere