He also wrote poems. Upon a snail was published posthumously in A Book for Boys and Girls: or Temporal Things Spiritualized. The poem is composed of two stanzas. Here's the molluscan bit. (The second stanza illustrates the religious significance of the snail's behaviour. If you desperately need to know the moral punchline, you can find it at any number of religious poetry sites.)
Upon a snail
She goes but softly, but she goeth sure,
She stumbles not, as stronger creatures do.
Her journey's shorter, so she may endure
Better than they which do much farther go.
She makes no noise, but stilly seizeth on
The flower or herb appointed for her food,
The which she quietly doth feed upon
While others range and glare, but find no good.
And though she doth but very softly go,
However, 'tis not fast nor slow, but sure;
And certainly they that do travel so,
The prize they do aim at they do procure.
