In the life of every man there are some elements that are practically inalterable while there are others which are subject to fluctuations, fortunate or unfortunate. The inalterable elements are taken for granted while those that fluctuate are matters for hope and fear.
Source: "The lessons of experience" (In: Mortals and Others: Bertrand Russell's American Essays, 1931-1935, v.1 (1975))
More info.: https://russell-j.com/HOPEFEAR.HTM