The ultimate equations [that would create a unified theory of physics] were their holy grail, their Kabbalah, and their philosopher's stone.
Holy Grail was said to have miraculous powers providing happiness, eternal youth or food infinite abundance. The search for the vessel became the principal quest of the knights of King Arthur.
Kabbalah is an discipline, and school of thoughts that originated in Judaisms. It seeks to define the nature of the universe and the human being, the nature and purpose of existence, and various other ontological questions.
Philosopher's stone is a legendary substance. It was sometimes believed to be an elixir of life, useful for rejuvenation and possibly for achieving immortality. For a long time, it was the most sought-after goal in Western alchemy.