Ah, just what I needed : Saussure à Meillet depuis Rome, 1904 :
... get the necessary rest, not later, but if possible immediately. ... I am trying the experiment at this moment, and regret not having decided sooner to interrupt my usual occupations and preoccupations completely. ... I am very well as a result, but would feel better still, as I was saying, if I had done it sooner. (J Joseph, 481).