Secret Matthew Gospel

Is the canonical Gospel of Matthew a genuine reproduction of Matthew's original autograph? Apparently not.

In SOD - Son of Man, page 46, Samuel F. Dunlap, quotes Jerome:

Writing to the Bishops Chromatius and Heliodorus, he complains [Jerome] that "a difficult work is enjoined, since this translation has been commanded me by your Felicities, which St. Matthew himself, the Apostle and Evangelist, DID NOT WISH TO BE OPENLY WRITTEN. For if it had not been SECRET, he (Matthew) would have added to the evangel that which he gave forth was his; but he made up this book sealed up in the Hebrew characters, which he put forth even in such a way that the book, written in Hebrew letters and by the hand of himself, might be possessed by the men most religious, who also, in the course of time, received it from those who preceded them. But this very book they never gave to any one to be transcribed, and its text they related some one way and some another.

This in turn is quoted in Isis Unveiled by H. P. Blavatsky, volume 2, chapter 4.

From this quote it is difficult to believe that Jerome was not in possession of the authentic Matthew - Chaldee language, Hebrew letters.

I did track down the original source of the above quote.

It comes from the preface to a "Pseudo-Matthew". Now whether or not the the Gospel is "pseudo" or not may be a matter of opinion; and whether Jerome's letter is real or not might also be a matter of conjecture. By the same token, we might question whether certain documents have been deemed spurious purely because they don't fit in with the status quo.

From the Wiki on the Gospel of the Nazarenes:

higher criticism argues that the canonical Gospel of Matthew is not a literal reproduction of Matthew's original autograph, but was rather the production of an unknown redactor, composed in Greek posthumous to Matthew. This aligns with Jerome's assessment, in which he stated, "Matthew, also called Levi, apostle and aforetime publican, composed a gospel of Christ at first published in Judea in Hebrew for the sake of those of the circumcision who believed, but this was afterwards translated into Greek, though by what author is uncertain."(Jerome, Lives of Illustrious Men, Chapter 3) 

Also on the above wikipedia entry, is a list of variances between the Canonical Matthew and the extant reconstructed text of Gospel of the Nazarenes.

So what proof do we have that Jerome didn't write the introductory letter that appears in the Gospel of the Pseudo Matthew?

 More about this Gospel:

"A narrative of the flight into Egypt is adorned with poetic wonders. The dragons, lions, and other wild beasts of the desert adore the infant Jesus. At His word the palm-trees bow their heads that the Holy Family may pluck their fruit. The idols of Egypt are shattered when the Divine Child enters the land. The "Gospel of the Nativity of Mary" is a recast of the Pseudo-Matthew, but reaches only to the birth of Jesus. It is extant in a Latin manuscript of the tenth century."