The two Isaiahs

Some divide Isaiah into two parts. This is sometimes called the "Detero-Isaiah Theory".

Chapters 1-39. The Isaiah.
Chapters 40-66. Another Isaiah. Some attribute this to his disciples.

Note: Chapter divisions were added in the Middle Ages, long after the NT (New Testament) canon had been decided.

John considers both the same Isaiah.

The name "Esaias" is a English transliteration of the Greek for "Isaiah".
The name "Isaiah" is an English transliteration of the Hebrew for "Isaiah".

Isaiah 53:1 Who hath believed our report? and to whom is the arm of the LORD revealed? [kjv]

κυριε τις επιστευσεν τη ακοη ημων και ο βραχιων κυριου τινι απεκαλυφθη [lxx]

John 12:38 That the saying of Esaias the prophet might be fulfilled, which he spake, Lord, who hath believed our report? and to whom hath the arm of the Lord been revealed? [kjv]

ινα ο λογος ησαιου του προφητου πληρωθη ον ειπεν κυριε τις επιστευσεν τη ακοη ημων και ο βραχιων κυριου τινι απεκαλυφθη [gnt]

John quotes the LXX (Septuagint).

Isaiah 53:1

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KJV: Who hath believed our report? and to whom is the arm of the LORD revealed?

Hebrew: מי האמין לשמעתנו וזרוע יהוה על מי נגלתה׃

Greek: κυριε τις επιστευσεν τη ακοη ημων και ο βραχιων κυριου τινι απεκαλυφθη

John 12:38

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KJV: That the saying of Esaias the prophet might be fulfilled, which he spake, Lord, who hath believed our report? and to whom hath the arm of the Lord been revealed?

Greek: ινα ο λογος ησαιου του προφητου πληρωθη ον ειπεν κυριε τις επιστευσεν τη ακοη ημων και ο βραχιων κυριου τινι απεκαλυφθη

John 12:39 Therefore they could not believe, because that Esaias said again, [kjv]

12:40 He hath blinded their eyes, and hardened their heart; that they should not see with their eyes, nor understand with their heart, and be converted, and I should heal them. [kjv]

12:41 These things said Esaias, when he saw his glory, and spake of him. [kjv]

John quotes from Isaiah, first and second parts, and appears to attribute it to the same Isaiah. Let us compare.

Isaiah 6:10 Make the heart of this people fat, and make their ears heavy, and shut their eyes; lest they see with their eyes, and hear with their ears, and understand with their heart, and convert, and be healed. [kjv]

επαχυνθη γαρ η καρδια του λαου τουτου και τοις ωσιν αυτων βαρεως ηκουσαν και τους οφθαλμους αυτων εκαμμυσαν μηποτε ιδωσιν τοις οφθαλμοις και τοις ωσιν ακουσωσιν και τη καρδια συνωσιν και επιστρεψωσιν και ιασομαι αυτους [lxx]

John 12:40 He hath blinded their eyes, and hardened their heart; that they should not see with their eyes, nor understand with their heart, and be converted, and I should heal them. [kjv]

τετυφλωκεν αυτων τους οφθαλμους και επωρωσεν αυτων την καρδιαν ινα μη ιδωσιν τοις οφθαλμοις και νοησωσιν τη καρδια και στραφωσιν και ιασομαι αυτους [gnt]

Isaiah 6:10

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KJV: Make the heart of this people fat, and make their ears heavy, and shut their eyes; lest they see with their eyes, and hear with their ears, and understand with their heart, and convert, and be healed.

Hebrew: השמן לב העם הזה ואזניו הכבד ועיניו השע פן יראה בעיניו ובאזניו ישמע ולבבו יבין ושב ורפא לו׃

Greek: επαχυνθη γαρ η καρδια του λαου τουτου και τοις ωσιν αυτων βαρεως ηκουσαν και τους οφθαλμους αυτων εκαμμυσαν μηποτε ιδωσιν τοις οφθαλμοις και τοις ωσιν ακουσωσιν και τη καρδια συνωσιν και επιστρεψωσιν και ιασομαι αυτους

John 12:39

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KJV: Therefore they could not believe, because that Esaias said again,

Greek: δια τουτο ουκ ηδυναντο πιστευειν οτι παλιν ειπεν ησαιας

John 12:40

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KJV: He hath blinded their eyes, and hardened their heart; that they should not see with their eyes, nor understand with their heart, and be converted, and I should heal them.

Greek: τετυφλωκεν αυτων τους οφθαλμους και πεπωρωκεν επωρωσεν αυτων την καρδιαν ινα μη ιδωσιν τοις οφθαλμοις και νοησωσιν τη καρδια και επιστραφωσιν στραφωσιν και ιασωμαι ιασομαι αυτους

John 12:41

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KJV: These things said Esaias, when he saw his glory, and spake of him.

Greek: ταυτα ειπεν ησαιας οτε οτι ειδεν την δοξαν αυτου και ελαλησεν περι αυτου