I just came across the following statement while learning Category Theory:
If $\mathcal{C}$ is a small category, then any functor $F: \mathcal{C} \to \mathbf{Set}$ may be expressed as a colimit in $[C, \mathbf{Set}]$ of a diagram of shape $(\mathbf{1}\downarrow F)^{op}$ whose vertices are representable functors, where $\mathbf{1}$ denotes a singleton set.
I can't seem to find a proof for it anywhere, does anyone know how to prove this?