I'm reading book "Geometric function theory and non-linear analysis" and there is one thing that I did not understand.
A curve family $\Gamma$ is a collection of curves. An admissible density is a Borel function $\rho$ for which $\int_\gamma\rho\,ds > \geqslant 1 \text{ for all } \gamma \in \Gamma$
The modulus of $\Gamma$ is $M(\Gamma) = > \operatorname{inf}\int_{\mathbb R^n}\rho^n(x)\,dx$ where the infimum is over all admissible densities for $\Gamma$.
The property I do not understand is
If $\Gamma$ contains a single "constant curve", then $M(\Gamma) = > \infty$.
I thought "constant curve" is just a point in $\mathbb R^n$. But what are admissible densities in this way?