Genshin Impact : The Meaning of Aeons

The Meaning of Aeons are one of three Weekly Boss materials dropped by Raiden Shogun. This boss is found at the End of the Oneiric Euthymia Domain underneath the Grand Narukami Shrine. Reference the image below for its location:

The Meaning of Aeons are awarded by challenging Memories: Guardian of Eternity on level II or higher. The recommended party level for this challenge is 70+. If this is one of the first three weekly boss domains you have challenged, collecting the rewards will cost 30 Resin. If you have already completed three weekly boss domains, the cost to collect materials is raised to 60 Resin. You can fight her as many times as you would like, but will only be able to collect materials one time per week. We recommend challenging her at the highest level you can to obtain the most rewards. Weekly Boss rewards reset every Monday at 4:00 AM server time.