An analysis by Jacques André of Book XII shows it contains 58 quotations from named authors and 293 borrowed but uncited usages: 79 from Solinus; 61 from Servius; 45 from Pliny the Elder. Isidore takes care to name classical and Christian scholars whose material he uses, especially, in descending order of frequency, Aristotle (15 references), Jerome (10 times), Cato (9 times), Plato (8 times), Pliny, Donatus, Eusebius, Augustine, Suetonius, and Josephus. He mentions as prolific authors the pagan Varro and the Christians Origen and Augustine. But his translator Stephen Barney notes as remarkable that he never actually names the compilers of the encyclopedias that he used "at second or third hand", Aulus Gellius, Nonius Marcellus, Lactantius, Macrobius, and Martianus Capella. Barney further notes as "most striking" that Isidore never mentions three out of his four principal sources (the one he does name being Pliny): Cassiodorus, Servius and Solinus. Conversely, he names Pythagoras eight times, even though Pythagoras wrote no books. The "Etymologies" are thus "complacently derivative".