Cosa significa nihil sine veneno praesertim dosi non servari?

Answer 1

Perhaps I can deal with the Latin text and rely on some kind soul to take things the rest of the way:

This Latin text, in the spelling Nil sine veneno presertim dosi non servari, is printed in the margin of page 21 of the German edition of the posthumous "Third Defense" of the Renaissance physician and alchemist Paracelsus (Phillip von Hohenheim, 1493-1541). It is a summary of the German sentence printed next to it, and can be translated "Nothing without poison, especially the dose not being considered", although the Latin syntax is quite unusual and may represent a printer's error.

The German text being summarized was Alle ding sind gifft/und nichts ohn gifft/Allein die dosis macht das ein ding kein gift ist.

Which can be translated All things are poison, and nothing is without poison; Only the dose causes a thing not to be poison.

When it came time to translate Paracelsus' German into Latin (as was done with many or all of his works, to make them more accessible to an international audience), the summarized sentence was given a fuller translation, as follows: Omnia venenum sunt, nec sine veneno quicquam existit; dosis sola facit ut venenum non sit.

In whatever verson (and all are cited), this statement of Paracelsus' is considered to be the founding principle of the field of toxicology.