Mysterious.

[M]ysteries have a longer half-life than puzzles, giving the example of Shakespeare, who commonly adapted story lines to his own ends up until the mid-1590’s. Around this time, his son passed away, and Shakespeare began to remove “crucial planks” from these older narrative structures, which created a greater sense of mystery because not everything in the narrative could be logically explained, in the way a puzzle can. This is also true in science. As Einstein remarked: “The most beautiful thing we can experience is the mysterious…It is the source of all true art and science.”

CONNECT