Our minds, like our bodies, are in continual flux; something is hourly lost, and something acquired.
 Samuel Johnson, The History of Rasselas, Prince of Abissinia (1759). copy citation

Context

“yet a new day succeeded to the night, and sorrow is never long without a dawn of ease. But they who restrain themselves from receiving comfort do as the savages would have done had they put out their eyes when it was dark. Our minds, like our bodies, are in continual flux; something is hourly lost, and something acquired. To lose much at once is inconvenient to either, but while the vital power remains uninjured, nature will find the means of reparation. Distance has the same effect on the mind as on the eye; and while we glide along the stream of time, whatever we leave behind us is always lessening, and that which we approach increasing in magnitude.” source