Heart of Darkness - Part I

Marlow is telling his story about his adventures in the Congo while aboard the Nellie on the Thames River. He uses the word "gloom" many times, such as "mournful gloom" and "brooding gloom" to represent darkness. Freslaven is the first example of what darkness can do and he is an example of deterioration resulting from darkness.
An example of black and white symbolism is the maps. The blank, or white, maps are good because they're unexplored. Eventually those blank spaces have been filled in and are black and dark because of colonization, which he is a part of. However, while other people are in it for reasons such as money, Conrad is in it for the adventure. He compares the river to a snake and says, "The snake had charmed me." A snake could devour a bird just like Africa could devour him.
He visits the doctor before his trip to the Congo, where his interaction with the doctor seems unusual. The doctor measures his skull and asks if there has been any madness in his family. Marlow asks the doctor if he will measure his skull when he gets back and the doctor says no because he doesn't think he'll see him again. He says goodbye by saying adieu, which is goodbye forever.
There are many moments where Conrad makes racist comments. For example, he writes, "Black rags were wound round their loins and the short ends behind waggled to and fro like tails. I could see every rib, the joints of their limbs were like knots in a rope, each had an iron collar on his neck and all were connected together with a chain whose bights swung between them, rhythmically clinking." He describes them like animals, but they are not his enemy.
In the second section, there are more examples of racism such as, "The pilgrims could be seen in knots gesticulating, discussing. Several still had their staves in their hands. I verily believe they took these sticks to bed with them."