All that we "know" is what registers on our brains, so what you perceive (your individual reality-tunnel) is made up of nothing but thoughts—as Sir Humphrey Davy noted when self-experimenting with nitrous oxide in 1819, and as Buddha noticed by sitting alone until all his social imprints atrophied and dropped away.
Yom Kippur, the Day of Atonement, is the holy of holies of Jewish time. It is that rarest of phenomena, a Jewish festival without food. Instead it is a day of fasting and prayer, introspection and self-judgment when, collectively and repeatedly, we confess our sins and pray to be written into God's Book of Life.