如何解释pieties?

有人问到这样一句话:

(1)I am sick of your melancholy histories, your sentimental pieties, your goddamned unchanging faces.

据我所知piety是一不可数名词,但此处却用作可数名词,如何解释呢?

piety作“虔诚”解的确是不可数名词,所以不少词典将它标作“[U]”。但piety有时亦可意指“虔诚的行为”,这时即可用其复形pieties,而这也正是上述句(1)中pieties的含义。再如:

(2)the small pieties with which they larded their discourse