caput Nili quærere or fontes Nili quærere
[i.e., to search for the head or source of the Nile]

A phrase the Romans applied metaphorically to problems that seemed unsolvable; hence, a mad endeavor.

Just yards downstream from the spring at Gish Abay, Ethiopia, source of the Blue Nile [2003 photograph courtesy of Pasquale Scaturro]

Blue Nile

• Pedro Páez (1564–1622) — Ethiopia (1603–1622)
• Jerónimo Lobo (1596?–1678) — Ethiopia (1624–1634)
• James Bruce (1730–1794) — Egypt, Sudan, Ethiopia (1768–1773)
• Pasquale Scaturro (American, b. 1953) — source to Khartoum (joining White Nile) to Mediterranean Sea

White Nile

• Sir Richard Francis Burton (1821–1890) and John Hanning Speke (1827–1864) — Tanzania (1857–1859)
• John Hanning Speke (1827–1864) and James Augustus Grant (1827–1892) — Tanzania, Uganda, Sudan (1860–1863)
• Sir Samuel White Baker (1821–1893) — Egypt, Ethiopia, Sudan, Uganda (1861–1865)