In Lois Lowry's novel "The Giver," Jonas is keeping a secret from the Giver. The secret is that he has been experiencing and learning about the true depth of human emotions and experiences, which he has received through the memories transmitted by the Giver.
Jonas decides to withhold this information from the Giver because he fears that if the Giver knows the extent of what Jonas has learned, it will place a heavy burden on the Giver, who has carried the memories alone for so long. Jonas is also concerned about the Giver's well-being and doesn't want to overwhelm him with the weight of the memories.
Ultimately, Jonas's decision to keep this secret reflects his growing sense of responsibility and his desire to protect the Giver, as well as his evolving understanding of the importance of the memories and the need to share them with the community.