Translation: In order to begin with the easiest, we place in review the theory of Epicurus, which is the best known to the majority. Here you will see Epicureanism set forth as accurately as it usually is by those who approve this doctrine.Ut autem a facillimis ordiamur, prima veniat in medium Epicuri ratio, quae plerisque notissima est. quam a nobis sic intelleges expositam, ut ab ipsis, qui eam disciplinam probant, non soleat accuratius explicari;
In translating I overlooked "non", because it's hard to believe that Cicero would begin by saying that Epicureanism is not usually explained accurately by its own adherents.
But it has to mean something, and I don't know what that may be.