A paradoxical Latin adage, which can be translated into "hasten slowly." It is often represented by the venerable Ancorra Secca emblem, which depicts a dolphin and an anchor intertwined. There are several different accounts of the saying's original origin, but nearly all of them include Erasmus of Rotterdam as being the first to put it into print. His most succinct explanation of the adage's meaning is:
the right timing and the right degree, governed alike by vigilance and patience, so that nothing regrettable is done through haste, and nothing left undone through sloth ...
The symbol's most famous usage is attributed to Erasmus' contemporary, Aldus Mantius, a.k.a. Aldo Manuzio, who used it as the emblem of his renowned Venetian print shop.


Sources:
http://www.mnemosyne.org/fr_festina.html
http://www.ancorasecca.it/PRESENTE.HTM
http://www.newadvent.org/cathen/09633b.htm