- Graduated from Michigan Agricultural College with an A.B. in Agricultural Science.
- Inherited a pile of money from his grandfather (who was around during the Civil War) and invested wisely in stocks and bonds, allowing him to live comfortably.
- Jonathan was admitted to the Capharnaum County Magician's Society on April 30, 1932, when he proved his abilities to other members of the Society by eclipsing the moon.
- Lived on Spruce Street, down by the waterworks, until he bought Isaac Izard's old house in 1943. Soon after moving in, he heard the sound of Isaac Izard's Doomsday Clock. At some point afterward, he bought a great number of clocks, using their ticking and ringing to drown out the sound of Isaac's clock.
- Converted the house to oil after buying it.
- Owns a piece of petrified wood from "out west".
- Owns a large, black 1935 Muggins Simoon.
- Created a magical illusion, the Fuse Box Dwarf, in the winter of 1948.
- Loved to get mail [The Figure in the Shadows; 29].
- Read in the tub [The House with a Clock in its Walls; 110].
- Knives make him nervous [The Figure in the Shadows; 19].
- Snores [The House with a Clock in its Walls; 82].
- Was interested in magic at an early age, and showed off his powers to a girl he liked, but it didn't work out. [The House with a Clock in its Walls; 177].
InspirationJonathan’s name stems from a highly-regarded Dutch statesman and leader of Dutch independence named Johan van Oldenbarnevelt (1547-1619), considered to some as the founding father of the Netherlands. He was executed on May 13, 1619, in The Hague by Prince Maurice of Nassau on a charge of subverting religion. Such an execution of a prominent citizen for political reasons, however in a religious disguise, in which the freedom of worship was involved, must have terrified the Pilgrim Fathers greatly, possibly leading to a decision to leave the country and bring them as the first Sabbath-keeping group to America.
Bellairs probably used the anglicized name after hearing of it in post-graduate English literature studies, specifically the play, The Tragedy of Sir John Van Olden Barnavelt (1619), written as a collaboration between John Fletcher (1579-1625) and Philip Massinger (1583-1640), playwrights of Shakespeare's era. Fletcher wrote 15 plays and is thought to worked with Shakespeare on The Two Noble Kinsmen and Henry VIII. Around 1605 he began to write plays in collaboration with Sir Francis Beaumont, and, before his death of the plague, produced numerous works with many collaborators.