Column separator extend above text

Question

I am working on a bilingual document with parallel text, occasionally interupted by monolingual sections (i.e. spanning the whole page width) in between. Each time the parallel text begins, the line I have dividing the columns extends above the top of the text, but is perfectly flush with the bottom. Is there a way I can get the line flush on both ends? The only thing I have figured out to try is to eliminate the space above the paragraph, but this apparently was not the problem. Many thanks in advance.

\documentclass{book}
\usepackage{paracol}
\begin{document}
\setlength{\columnsep}{1em}
\setlength{\columnseprule}{0.4pt}
    \begin{paracol}{2}
    Accipio.
    \switchcolumn
    I do accept it.
    \end{paracol}
\end{document}

Answer 1

The first baseline is controlled by \topskip

\documentclass{book}
\usepackage{paracol}
\setlength\textwidth{6cm}%just  for demo
\begin{document}
\setlength{\columnsep}{1em}
\setlength{\columnseprule}{0.4pt}
\setlength\topskip{7pt}
    \begin{paracol}{2}
    Accipio.
    \switchcolumn
    I do accept it.
    \end{paracol}
\end{document}