  We provide an intuitive understanding of the collective low-energy spin
excitation of the one-dimensional spin-1/2 antiferromagnetic Heisenberg chain,
known as the spinon. To this end, we demonstrate how a single spinon can be
excited by adding one extra spin to the ground state. This procedure accurately
reproduces all key features of the spinon's dispersion. These follow from the
vanishing norm of the excited state which is triggered by the ground state
entanglement. Next, we show that the spinon dispersion can be approximately
reproduced if we replace the true ground state with the simplest valence-bond
solid. This proves that the spinon of the one-dimensional Heisenberg model can
be understood as a single spin flowing through a valence-bond solid.
