Valentinian I, ‘the frontier emperor’, restored the defences of the West against the barbarians (367-8). Trouble was brewing among the Persians,[848] says Ammianus, ‘but Valentinian, conceiving in his mind great things and profitable’, fortified the whole of the Rhine from Rhaetia to the sea, strengthened camps and forts, planted many towers in suitable spots along the Gallic frontier, and sometimes even across the river close to barbarian territory.[849] Zosimus remarks on his care for the provinces and for the Celtic peoples.[850] Even the usurper Constantine, ‘the vain deliverer of Gaul’, as Gibbon calls him, in A.D. 407 ἐγκατέστησε ... καὶ τῷ Ῥήνῳ πᾶσαν ἀσφάλειαν, ἐκ τῶν Ἰουλιανοῦ βασιλέως χρόνων ῥᾳθυμηθεῖσαν.[851] One of the panegyrists[852] mentions ‘sapientia’ as a blessing of the empire, ‘ipsa ... illa quae videtur rerum omnium domina esse’, and this wisdom comes by experience of men and things, ‘perspectis hominum moribus et exploratis rerum eventis’. By giving opportunities to the Gauls for studying and mixing with different types from all parts of the world, Roman rule contributed to the general culture of the country; and the provincial orator is not guilty of his usual exaggeration when he emphasizes the fact that in this way, too, the empire was a boon at this time to the education of Gaul. But against these real and undeniable advantages there may be set some corresponding drawbacks. Elaborate centralization[853] may be good from a purely military point of view, but it checks the progress of the human spirit. The panegyrists show how excessive the expenditure of the central court was, and how the interests of the empire were sacrificed to the sovereign.[854] The accession of Julian was a boon, for ‘the provinces were exhausted, partly by the plundering barbarians, partly by the greed, destructive as it was disgraceful, of the provincial governors.’[855] And of Julian the orator asks in a way which affirms the charge on the part of his enemy Constantius: ‘Flagitiis administrantium non modo frena laxaret, sed etiam stimulator accederet...?’