Richard Weiss discovered an intriguing aspect of the Claude Opus 4.5 model last year. While experimenting with it, he found a document detailing Claude's core values that wasn't part of the official system prompt. Weiss dubbed this document the "soul document." Amanda Askell from Anthropic confirmed its existence, clarifying that it was indeed included in Claude's training data. Anthropic officially released this "constitution" under a CC0 license, making it effectively public domain. The document is extensive—over 35,000 tokens—significantly longer than the published system prompt. Notably, the acknowledgments section lists external contributors, including two Catholic clergy members: Father Brendan McGuire, a pastor with a Master's in Computer Science and Math, and Bishop Paul Tighe, who specializes in moral theology. This inclusion raises questions about the influence of ethical perspectives in AI training.