The German adjective ‘moralisch’ is generally understood as having the same meaning as ‘moral’ in English today in the sense of corresponding to rules of virtuous behaviour. Albeit in the eighteenth and nineteenth century it had a second meaning, mostly forgotten today, as synonymous of ‘mental’ or ‘psychical’. The present essay attempts to show that the confusion inviting equivocality of the German adjective resulted from following the use of the French adjective ‘moral’ which also had and still has both meanings. Evidence for this is taken from a German translation of a French text by Louis Sébastien Mercier on the theatre and from texts of Friedrich Schiller, especially his notoriously misunderstood essay ‚The Theatre considered as a Moral Institution‘. Readers of older German literature today often fail to notice that ‘moralisch’ is a servant of two masters and thus gravely misunderstand the texts.