The 1531 publication in Augsburg of the first emblem book, the Emblemata of the Italian jurist Andrea Alciato launched a fascination with emblems that lasted two centuries and touched most of the countries of western Europe. “Emblem” in this sense refers to a didactic or moralizing combination of picture and text intended to draw the reader into a self-reflective examination of his or her own life. 
One of such books was the Symbolorum et Emblematum by Joachim Camerarius (1534-1598), whose fourth volume containing several snail examples appeared posthumously in 1604 .
The book contains one page with an essay in Latin, on the opposite page an emblem along with a Latin distich .
Today emblem XCVIII Nec te quaesiveris extra. The distich is Non tibi tela nocent latitanti, erumpere at ausum / Configunt: temere qui ruit, ille perit.
The snail is rather stylised, with two tentacles and a sort of humanised eye and eyebrow; the shell is imaginary, but the whole picture points at a land snail.
Gibbs explains  this as “The title comes from the Roman satirist Persius, urging you not to go extra, outside, yourself. This self-containment is expressed emblematically in the form of a snail. The first line of the poem sets up the contrast between the man who hides and the man who boldly burst out – weapons strike the bold man, but not the one who hides. The second line repeats the idea that the bold man who rushes ahead will perish; again, the snail is a great contrast to the idea of anyone rushing into anything. Sadly, because the poor snail in the emblem did come out of his shell, he has been struck by one of those arrows!”.
Perhaps the snail met one of those medieval knights?
 Digitally available in Münchener Digitalisierungs Zentrum, urn:nbn:de:bvb:12-bsb00028237-8.
 Many of these distichs have been explained in detail by Laura Gibbs on her excellent blog: distichlatina.blogspot.nl.
 http://bit.ly/1fqIwr4 (13.i.2014).