Where argument begins, however, is where it has always begun, ever since Conrad struck the ‘last note’ in Heart of Darkness: the debate over what the book’s sombre theme actually is. The debate is not just ongoing, it is yawning. Over a century after it was written, diametrically opposed conclusions are still being drawn about Heart of Darkness. Some critics view it as deeply racist, while others see it as an attack on the racism of colonialism; some critics view the book as largely psychological, while others believe it to be mostly historical; some believe it is a critique of the corrupting power of wilderness, while others believe it a parable of humanity’s weakness no matter what its setting.

In terms of narrative structure, Youth is very similar to Heart of Darkness. Conrad’s seafaring narrator, Charlie Marlow, appears first in Youth, telling an assembly of four unnamed characters – another narrator, a lawyer, an accountant and a director of companies – a story from his time away at sea, and a near identical frame is used in Heart of Darkness. But between the first book and the second, there is a quantum leap in scope, ambition and sophistication. In literary terms Youth is an adolescent while Heart of Darkness is a fully formed adult.

Both stories were based on Conrad’s own experiences as a merchant sailor and it is hard to overestimate the role and influence of his maritime career. He was no junior deckhand who spent a few months as crew on a clipper round Cape Horn for the thrill of it. Conrad spent twenty years at sea between the ages of 16 and 36, and saw much more of the world than was normal for people in the late nineteenth century. The sea was his alma mater and he worked hard not just as crew member but at his studies, learning English (his mother tongue was Polish and he spoke French, Russian and German before tackling English) to a sufficiently high level that he could qualify as a Master Mariner in the British merchant navy, a significant seafaring achievement. Conrad is remembered as an accomplished writer who was also a mariner. His old shipmates might remember him better as an accomplished mariner who was also a writer.

His two decades as a sailor provided the seam of experience from which he mined his early fiction. In Youth, a novel that deals with the young’s perception of their own invincibility, Marlow describes a journey that ended in disaster with his boat catching fire and sinking off the East Indies, forcing the 20-year-old to put to sea in an open boat. It is a dramatic story of bravery and determination but this exact same thing happened to Conrad early in his career at sea.

Today a survival story like that would be turned instantaneously into newspaper features and film scripts but Conrad lived in a more thoughtful age. It churned in his mind for years before finally emerging as a novel, not as a swashbuckling story but as an observation on the untrammelled optimism of the young. In his 1917 author’s note, he wrote: ‘Youth is a feat of memory. It is a record of experience; but that experience, in its facts, in its inwardness and in its outward colouring, begins and ends in myself.’