PS -- I don't mean the obvious by that question -- it could be helpful to explain to a child lost and dying in the desert, for example, that the "oasis" they "see" in the distance is nothing but an optical illusion. Might save them some steps.

But how is it helpful to tell someone, for example, that the correlations they experience between planetary transits and personal moods/inclinations/daily life experiences are not scientific "facts" and are therefore not "real"??? Such observations and experiences are very "real" indeed -- and delightfully so.