  \psset{linecolor=lightgray}
  \pstextpath
    {\pscurve(-4,-2)(-2,0)(0,-3)(2,-1)(3,-3)}
    {\color{blue} If you
    want to type  $2=\int_0^\pi \sin\theta\,
    \mathrm{d}\theta$ and let it follow
    along a curving line \ldots}
