Not every essay stands alone. Some are written as a series, a handful of pieces meant to be read one after another, and those live under the Collections tab on the Essays page, next to Recent and Search.
Each collection lists its parts in the order they were written to be read, not the order they happened to publish, and Begin Reading takes you straight to the first one. The essay pages themselves keep that same order at the bottom, so once you start a series the next part is one click away without going back to find it. If a single essay left you wanting more on the same subject, check here before you assume there is nothing else.