King of Siam
"He was the first modern man of Thailand," says Attachak Sattayanurak, a history professor at Chiang Mai University.
"He ensured that religion, astronomy and science prospered during his reign," says news reporter and former politician Sansanee Nakpong.
"He was interested in the civilisation and technology of the West," says Chulalongkorn University historian Dhiravat na Pombejra.
Newspaper columnist Steve Rosse calls him a "Renaissance man". A Renaissance man is someone with many broad interests and with the opportunity to learn a great deal about each of them. And the phrase fits Rama IV perfectly.
As a lad, he learned riding, shooting and fencing.
During his 27 years as a monk, he studied Latin and English, which enabled him to read texts on science, geography, history, mathematics and astronomy.
On the receiving end of technology, he was the first Thai king to be photographed.
One of his greatest accomplishments, however, caused his death. He correctly calculated the time and place of a total eclipse of the sun, which occurred on August 18, 1868, and pinpointed a remote village in Prachuab Khiri Khan, on the west coast of the Gulf of Siam, as the place where it could be clearly seen.
The eclipse occurred exactly as Mongkut had predicted, and European scientists on hand conceded that he was a brilliant mathematician and a real astronomer.
But the pavilion to view the eclipse had been in a place that had a lots of mosquitoes. Soon after his return to Bangkok, Mongkut fell ill from malaria, and would never recover.
-- From Nation Junior