  We study the spectral function of the axial-vector charmonium state
$\chi_{c1}(2P)$ coupled to $DD^{\ast}$ mesons, by employing a quantum field
theoretical approach: a pronounced enhancement close to the $D^{0}% D^{\ast0}$
threshold, to be identified with the $X(3872)$, emerges. In the complex plane
we find two poles: a pole for the broad seed state $\chi_{c1}(2P)$, and -- in
the easiest scenario -- a virtual pole for the $X(3872)$. Thus, our approach
describes both the seed state and the dynamically generated $X(3872)$
simultaneously. In particular, it explains the most prominent, both
molecular-like and quarkonium-like, features of the $X(3872)$: its very small
width (the decay into $D^{0}D^{\ast0}$ is predicted to be about 0.5 MeV), the
enhanced radiative decay into $\psi(2S)\gamma$ w.r.t. $\psi(1S)\gamma$, and the
isospin breaking decay into $J/\psi\rho$ (thanks to $DD^{\ast}$ loops mediating
this decay channel). At the same time, we aim to determine the pole position
and the properties of the charmonium seed state: quite interestingly, even if a
pole is always present, it is possible that there is no peak corresponding to
this state in the spectral function, thus potentially explaining why the
corresponding resonance could not yet be seen in experiments.
