Muss ist eine harte Nuss—Must is a hard nut to crack. Ger. Pr.

Müsset im Naturbetrachen / Immer eins wie alles achten; / Nichts ist drinnen, nichts ist draussen, / Denn was innen, das ist aussen. / So ergreifet ohne Säumness / Heilig öffentlich Geheimniss—In the study of Nature you must ever regard one as all; nothing is inner, nothing is outer, for what is within that is without. Without hesitation, therefore, seize ye the holy mystery thus lying open to all. Goethe.

Müssiggang ist aller Laster Anfang—Idleness is the beginning of all vices.

Must is a hard nut to crack, but it has a sweet 30 kernel. Spurgeon.

"Must" is hard, but by "must" alone can man show what his inward condition is. Any one can live unrestrainedly. Goethe.

Must not a great history be always an epic? Dr. Walter Smith.

Mutability is the badge of infirmity. Charron.

Mutare vel timere sperno—I disdain either to change or to fear. M.

Mutatis mutandis—After making the necessary 35 changes. L.

Mutato nomine, de te / Fabula narratur—Change but the name, the story's told of you. Hor.