The title refers, of course, to Matthew (2:12) *''And being warned in a dream not to return to Herod, they departed to their own country by another way''*. To be honest, it is not that specific particular case I'm more interested in. I'd like to have a reference, or a hint here, for a simple proof of the following fact (intuitive, but not easy to proof, as usual in these matters). > Let $\Gamma$ be a simple Jordan arc in > $\mathbb{R}^2$ (a homeomorphic image > of the interval $[0,1]$). Then, $\Gamma$ > can be included in a simple Jordan > loop $ \Sigma $ (a homeomorphic image > of $\mathbb{S}^1$). By the (generalized) Jordan's theorem, we know that $\mathbb{R}^2\setminus\Gamma$ is connected; and being open, it is even connected by piece-wise linear paths. The difficulty is that we need a path connecting the end-points of $\Gamma$; in other words, the question is how to show that $(\mathbb{R}^2\setminus\Gamma)\cup \partial\Gamma $ is path-connected (after that, an injective path could always be extracted). It seems to me everything would follow easily from this lemma: > Assume that $B(0,2)\setminus \Gamma$ > has at least two connected components > that meet $B(0,1)$. Then, there are > three consecutive points of $\Gamma$, > resp. $y_1$, $y_2$, and $y_3$ such > that $\|y_2\|=1$, and > $\|y_1\|=\|y_3\|=2$ I'm also a bit puzzled by the quantitative aspect of this problem: > Assume that $\Gamma$ is parametrized > by a homeomorphism > $\gamma:[0,1]\to\Gamma$ with a modulus > of continuity $\omega(t)$ (say, a > continuous concave function vanishing > at $t=0$) and let $\omega_1$ be > another modulus of continuity such > that $\omega_1(t) > \omega(t)$ for $t > 0$. > Is there a Jordan loop $\Sigma$ with parametrization $\gamma_1[0,2 > ]\to\Sigma$ that has modulus of > continuity $\omega_1$ ?