Proposition 8.3.0.1 (Yoneda's Lemma, Weak Form). For any (locally small) category $\operatorname{\mathcal{C}}$, the Yoneda embedding
\[ \operatorname{\mathcal{C}}^{\operatorname{op}} \rightarrow \operatorname{Fun}( \operatorname{\mathcal{C}}, \operatorname{Set}) \quad \quad X \mapsto h^ X \]
is fully faithful.