Jacobus Kapteyn Quote
Undoubtedly one of the greatest difficulties, if not the greatest of all, in the way of obtaining an understanding of the real distribution of stars in space, lies in our uncertainty about the amount of loss suffered by the light of the stars on its way to the observer.
On the Absorption of Light in Space, The Astrophysical Journal, Volume XXIX, Number 1, January, 1909
