The answer is: A man clothed in linen

Daniel 10:5

In the Book of Daniel, when he gazes by the river Hiddekel, he is surrounded by overwhelming spiritual symbolism and life-changing encounters. The "man clothed in linen" is a fascinating figure, often understood to be a divine messenger, echoing themes of other biblical beings like angels, who appear with a similar flourish.

Now, let’s take a moment to appreciate the river Hiddekel itself, known in modern terms as the Tigris River. This formidable natural landmark highlights an often-overlooked feature of ancient settings. Rivers weren't just geographical features; they were vital for trade, sustenance, and the lifeblood of cities. The Waters of Hiddekel produced grain and supported life in what is historically recognized as the cradle of civilization. It's surprising to note that this area is where some of the earliest written records were found, showcasing a rich reservoir of knowledge and culture.

On that fateful moment by the river, Daniel didn't just have an ordinary vision; he was seemingly plunged into a divine realm. If you consider the wide sweep of biblical narrative, such interactions by rivers occur throughout the texts—think Moses at the Nile or Jesus being baptized in the Jordan, both speaking volumes about transformation and revelation. The parallels hint at a rich tapestry of cognitive and spiritual journeys that intertwine under the expansive sky of human experience.

Daniel's vision, thus, was more than an encounter; it was a profound window into a cosmic narrative of divine communication that weaves through more than just one character's story, revealing universal themes of message, purpose, and clarity. It is pretty captivating!