There are several facts that have to be noticed before we can arrive at a clear understanding of all the denials recorded of Peter by the four evangelists:—

 I.  We have to note that the fact that Peter would deny His Lord was foretold in three distinct prophecies uttered on three separate occasions, and differing both as to the occasion and as to particulars.

 1.  The first was in the upper chamber, recorded in John 13:38. It was absolute as to the fact, general as to the day, but particular as to the number of denials: "a cock shall by no means crow [from this time forth] until thou hast denied Me thrice" (see Appendix 156).

 2.  The second was in the upper chamber, recorded by Luke 22:34. It was after the "strife", and immediately before leaving the room. It was absolute as to the fact, but particular as to the day and the number of the denials: "a cock shall not crow this day, before thou wilt thrice deny that thou knowest Me" (see Appendix 156).

 3.  The third was after the Lord had left the city and immediately before entering the garden of Gethsemane. It is recorded in Mark 14:30, and was particular in every detail: "Verily I say unto thee that (hoti) thou (added by all the texts) this day, in this night, before a cock crow twice, thrice thou wilt deny Me". Compare the fulfillment, and see Appendix 156.

  This last prophecy furnishes the key to the whole problem. For, note:—
       (a) that a cock was to crow twice, and
       (b) that Peter would deny thrice;
that is to say, before each of the two cockcrowings Peter would thrice deny His Lord. This is confirmed by the repetition in the fulfillment (Mark 14:72).

  Thus, there would be six denials in all; three before each cockcrowing.

  Note that the word "cock" has no Article in any of the four records: in each case it is not "the", but "a cockcrowing".

 II.  Consonant with these data, we have the remarkable fact that Matthew, Luke, and John each record three denials, and one concluding cockcrowing. Mark also records three denials, but mentions the two cockcrowings.

  Consequently, in the four Gospels there are no less than twelve denials mentioned. And the questions are, which of these are duplicates, and which are the resulting six required by the Lord's third prophecy in Mark 14:30?

 III.  If we note accurately the marks of time in each Gospel, the place, and the persons addressing Peter, every condition required by each of the Greek words employed is fully and perfectly satisfied, without a shadow or suggestion of "discrepancy".

 i.  The First Series of Three.

 1.  The First Denial, John 18:17. Place: the door (thura) without. Time: entering. The questioner: the porteress (Greek thuroros).

 2.  The Second Denial, Matthew 26:70 (Mark 14:68). Place: the hall (aule). Time: sitting. Questioner: a certain maid. Luke 22:56-58 combines the same place and time, with the same maid, and another (heteros, masculine).

 3.  The Third Denial, Matthew 26:71. Place: the gateway, or porch (pulon). Time: an interval of an hour. John 18:25, 26 combines the same place and time, with another maid and bystanders, one of them being a relative of Malchus.

A COCK CREW.
(Mark 14:68. John 18:27.)

 ii.  The Second Series of Three.

 1.  The First Denial, Mark 14:69. Place: "beneath in the hall". Time: shortly after. Questioner: the maid again.

 2.  The Second Denial, Matthew 26:73 (Mark 14:70). Place: the gate (pulon). Time: shortly after. Questioners: the bystanders.

 3.  The Third Denial (Luke 22:59, 60). Place: the midst of the hall (aule, verse 55). Time: "an hour after" (verse 59). Questioner: a certain one (masculine).

A COCK CREW.
(Matthew 26:74. Mark 14:72. Luke 22:61.)

 IV.  We thus have a combined record in which there remains no difficulty, while each word retains its own true grammatical sense.