# Multiple lines of centered text in between curly brackets

I would like to have several blocks of centered text and math within pairs of tall curly brackets, linked by arrows, similar to the following picture.

How can I achieve this?

You could use parbox

\documentclass{article}
\usepackage{amsmath}
\usepackage[margin=2in]{geometry}
\begin{document}

\begin{align}
\aleph : \left\{ \parbox[c]{1.1in}{\centering
Nash components\\with respect to X}
\right\}
\rightarrow
\left\{ \parbox[c]{1.1in}{\centering
essential divisors\\over X}
\right\}
\end{align}
is the \itshape{Nash map}.
\end{document}