Treat people as an end, and never as a means to an end - Immanuel Kant

Chisels and hammers may suffice to work a piece of wood, but for etching we require an etcher's needle. Thus common sense and speculative understanding are both useful, but each in its own way: the former in judgments which apply immediately to experience; the latter when we judge universally from mere concepts, as in metaphysics, where sound common sense, so called in spite of the inappropriateness of the word, has no right to judge at all.

Il difetto di giudizio è propriamente quello che si chiama stupidità, difetto cui non c'è modo di arrecare rimedio. Una testa ottusa o limitata, alla quale non manchi altro che un conveniente grado di intelletto […], si può ben armare mediante l'insegnamento fino a farne magari un dotto. Ma, poiché in tal caso di solito avviene che sia sempre in difetto di giudizio […], non è raro il caso di uomini assai dotti, i quali nell'uso della loro scienza lasciano spesso scorgere quel tal difetto, che non si lascia mai correggere.

[Religion should be] .... successively freed from all statutes based on history, and one purely moral religion rule over all, in order that God might be all in all. The veil must fall. The leading-string of sacred tradition with all its appendices becomes by degrees useless, and at last a fetter … The humiliating difference between laymen and clergymen must disappear, and equality spring from true liberty. All this, however, must not be expected from an exterior revolution, which acts violently, and depends upon fortune In the principle of pure moral religion, which is a sort of divine revelation constantly taking place in the soul of man, must be sought the ground for a passage to the new order of things, which will be accomplished by slow and successive reforms.