From The Guardian:
On Saturday 6 August 1763 James Boswell, then aged 22, boarded the Prince of Wales packet boat at Harwich, on the coast of Essex. The ship was bound for the Dutch port of Helvoetsluys; from there, Boswell travelled to the university town of Utrecht where, at the insistence of his father, he was to study law. He was being punished for his scandalous life in London – he'd lately converted to Catholicism and fathered an illegitimate son whom he would never see – but none of this quite explains his dismal mood in the days before he left for Holland. His friend and mentor Samuel Johnson found him agitated, gloomy and dejected as they shared the journey to Harwich. The elder man was moved to remark of a moth that burned itself to death in a candle flame: “That creature was its own tormenter, and I believe its name was Boswell.”
The reluctant scholar's spirits had sunk even lower by the time he reached Utrecht. He was not cheered by his lodgings, next door to the town's half-ruined cathedral, and “groaned with the idea of living all winter in so shocking a place”. He woke the next day in profound despair and ran out into the streets, convinced he was going mad. He groaned aloud as he turned from the cathedral square, cried out as he crossed the city's turbid canals and wept openly in the faces of passing strangers. In the weeks that followed, Boswell's letters traced a pitiful decline; to his friend William Temple, he described a wretchedness that, he insisted, nobody who had not suffered it could fully comprehend. “I have been melancholy,” he wrote, “to the most shocking and tormenting degree.”
More here.