Is it 'If Philip possessed a single virtue it has eluded the conscientious research of the writer of these pages. If there are vices--as possibly there are--from which he was exempt, it is because it is not permitted to human nature to attain perfection even in evil.'?


Google Books (http://books.google.com/books?id=D3hKpTRLKkwC&pg=PA498&lpg=PA498&dq=motley+philip+ii&source=web&ots=ONOUvYnpUe&sig=Rhsq4HRWlCAJ3mrKDqI8RtRTxxE#PPR15,M1) has the entire text; from what I can tell at a quick glance it's on pp. 534-5 of Chapter 35.