found this via Margaret Aston. Lollards and Reformers: Images and Literacy in Late Medieval Religion (Hambledon Press, 1984), 110, who summarizes some of this passage like so:
there was a certain inconstancy among the heretics for thus ‘venerating, kissing, and saluting the Gospel, revering the very manuscript’, while simultaneously claiming that living tress were more worshipful than carved imaged. By the same token should not the care they bestowed on their texts, protecting them from dirty hands and drops of rain, more logically be bestowed on living creatures — sheep (rather than dead vellum), dogs, or flies?
from Thomas Netter, Doctrinale Antiquitatum Fidei Catholicae Ecclesiae, ed. B. Blanciotti (Venice, 1757-59), iii, col. 94, available from Google Books (but oddly not Archive.org), here.
Also note “I with all the faithful worship the dead Christ and despise the living Jews” for yet more evidence of the centrality of antisemitism to late medieval Christianity.