is one allowed to wear glasses on Shabbos when the lenses change colors in the sun and indoors?
דבר דבר (Dabair Davar): A Possible Distinction Between Two Types of מצות (Mitzvos);
Various Examples of Where We Have the Problem of דבר דבר (Dabair Davar) and ממצוא חפציך (Mimtzo Cheftzecha);