Third paper in the SAE Introduction to Learning series. Addresses 14DD (purpose layer) learning. Core claim: the establishment of directionality in learning cannot be reduced to "usefulness" — it must take the form of "cannot not." Defines 14DD through three necessary conditions (sustained 13DD scrutiny, non-extinguishability under social opposition, behavioral compulsion) and restates the definition using Via Negativa tools (exclusion principles, locking principle, ρ-limit) from SAE Methodology Paper VII. Introduces calling, SDT, and sacred values literature as empirical calibration. Identifies three forms of 14DD colonization (direction substitution, superego internalization, full-support resistance removal). Education section argues that cultivation at 14DD is negating false "cannot nots" rather than implanting direction, grounded in Paper VII's R7 "need not" principle. Bridges to 15DD learning (recognizing the other's purpose). SAE学习导论系列第三篇。讨论14DD(目的层)学习。核心命题:学习方向感不能还原为"有用",必须是"不得不"。给出三条件定义(持续13DD审视、社会性外部否定不可熄灭、行为性),借助方法论七的排除律/锁定律/ρ-limit工具重述。引入calling、SDT、sacred values文献校准。识别三种14DD殖民形态。教育部分基于R7"不必然"原则。桥接15DD学习。 Chinese authoritative, English independent rewrite (not translation). Keywords Self-as-an-End, SAE, DD sequence, 14DD, purpose, learning, cannot not, calling, Self-Determination Theory, sacred values, Via Negativa, exclusion principle, locking principle, colonization, cultivation, education, motivation, negative methodology Language zho (Chinese, primary); eng (English, independent rewrite) License CC BY 4.0 Related identifiers Is part of (SAE Learning Series) 10.5281/zenodo.19426123 (Learning Series Paper 1: 11DD+12DD) 10.5281/zenodo.19436811 (Learning Series Paper 2: 13DD) References 10.5281/zenodo.18528813 (SAE Paper I) 10.5281/zenodo.18727327 (SAE Paper III — DD Sequence) 10.5281/zenodo.18914682 (ZFCρ Paper I) 10.5281/zenodo.19321417 (SAE Psychoanalysis Paper III) 10.5281/zenodo.19358010 (SAE Economics Series, first paper) 10.5281/zenodo.19481305 (SAE Methodology Paper VII — Via Negativa) Is continued by (planned) Learning Series Paper 4: 15DD (learning to recognize the other's purpose) AI Use Declaration Claude (Anthropic) served as primary writing partner. ChatGPT, Gemini, Grok, and Claude provided peer review. Deep research on calling, SDT, sacred values, and purpose-driven learning was conducted via ChatGPT deep research. All theoretical decisions, corrections, and final judgments are the author's.