Tertullian - Against the Valentinians

In Which the Author Gives a Concise Account of, Together with Sundry Caustic Animadversions on, the Very Fantastic Theology of the Sect. This Treatise is Professedly Taken from the Writings of Justin, Miltiades, Irenæus, and Proculus. ———————————  
"The Valentinians, who are no doubt a very large body of heretics—comprising as they do so many apostates from the truth, who have a propensity for fables, and no discipline to deter them (therefrom) care for nothing so much as to obscure what they preach, if indeed they (can be said to) preach who obscure their doctrine. The officiousness with which they guard their doctrine is an officiousness which betrays their guilt. Their disgrace is proclaimed in the very earnestness with which they maintain their religious system. Now, in the case of those Eleusinian mysteries, which are the very heresy of Athenian superstition, it is their secrecy that is their disgrace."