At times his view of the past consists of nothing but grey patches, then at others images appear of such extraordinary clarity he feels he can scarce credit them – such as that of General Marmont, whom he believes he saw at Martigny to the left of the track along with the column he was moving, clad in the royal- and sky-blue robes of the Councillor of State, and image which he still beholds precisely thus, Beyle assures us, whenever he closes his eyes and pictures that scene, although he is well aware that at that time Marmont must have been wearing his general’s uniform and not the blue robes of state.
Beyle furthermore writes that even when the images supplied by memory are true to life one can place little confidence in them. Just as the magnificent spectacle of General Marmont at Martigny before the ascent remained fixed in his mind, so too, after the most arduous portion of the journey was done, the beauty of the descent from the heights of the pass, and of the St Bernard valley unfolding before him in the morning sun, made an indelible impression on him. He gazed and gazed upon it [...] Beyle writes that for years he lived in the conviction that he could remember every detail of the ride, and particularly of the town of Ivrea, which he beheld for the first time from some three-quarters of a mile away, in light that was already fading. [...] It was with severe disappointment, Beyle writes, when some years ago, looking through old papers, he came across an engraving entitled Prospetto d’Ivrea and was obliged to concede that his recollected picture of the town in the evening sun was nothing but a copy of that very engraving. 

Sebald, W.G. (originally 1990) (2002) Vertigo (trans. Hulse, M) London: Vintage p.5, 7, 8