In Müller-Schubert’s Winterreise the sixth lied begins with
Manche Trän’ aus meinen Augen
ist gefallen in den Schnee: (…)
Why is Manche Trän(e[n]) in singular? Is this rather a “I have to accept it like this because it’s poetry” and in that case I’d like to know the meaning or effect of using the singular, or, I need to think of it as meaning sind gefallen instead (which I doubt).
Or, is Manche and not manche? That is, it’s a noun (which I also doubt, since I cannot find it as a noun in the dictionaries).