6:2 seraphim. This is the plural of “seraph,” a Heb. term meaning “burning” or “glowing” that probably corresponds to the “living beings” of Rev 4:6–9 that also had six wings. Miscall (1993:34) suggests some wordplay here (not at all unusual for Isaiah) and notes that “seraph” (sarap [TH8314, ZH8597]) is very similar to another Heb. root, tsarap [TH6884, ZH7671], meaning “purge” in 1:25. He also notes the use of sarap [TH8313, ZH8596] in 1:7, as well as the use of both roots in 6:6. Although the seraphim are not mentioned elsewhere, see the description of the cherubim in Ezek 1:1–28; 10:1–22; Rev 4:8.

6:3 Holy, holy, holy. The Heb. triple usage is for emphasis (cf. the triple use of the Heb. for “Temple of the Lord” in Jer 7:4, where the NLT translates the Heb. as “repeated”). This is the only place a threefold use of a single word is found in the Heb. Bible (cf. its echo in Rev 4:8). However, even a twofold use of a word can express a superlative or indicate totality (the DSS copy of Isaiah, 1QIsaa, only has the word twice).

6:6 burning coal he had taken from the altar. Coals of fire were taken inside the Most Holy Place on the Day of Atonement, when sacrifice was made to atone for sin (Lev 16:12).

Listen carefully. The Heb. imperatives mean “Listen carefully” (shimʿu [TH8085, ZH9048]) but “do not understand,” and “watch closely” (reʾu [TH7200, ZH8011]) but “learn nothing.” Both are followed by infinitive absolutes that usually indicate continuous action in this position (when they follow their cognate finite verbal forms). The negatives “not understand” and “learn nothing” are qal imperfects with imperative force, as the prohibitive particle ʾal [TH408, ZH440] indicates. Apparently, the verbs are meant to convey sarcasm and underscore the total refusal of the people to listen to the prophet’s message. The entire subject of obduracy is complex and variously understood, but see Chi (1974) and Chisholm (1996). Modern English versions use a variety of translations to render the meaning of the Heb. syntax: “Be ever hearing, but never understanding” (NIV); “Keep listening, but do not comprehend” (NRSV); “However hard you listen, you will never understand” (REB); “Listen carefully, but you shall not understand!” (NAB); “Listen and listen, but never understand!” (NJB); “Hear, indeed, but do not understand” (NJPS).

6:10 This verse contains a literary feature known as a chiasm, a common literary device in the OT. It consists of an abc/cba inversion of terms: hearts … ears … eyes/eyes … ears … hearts.

Harden the hearts of these people. The Heb. lit. says, “Make the heart of this people fat,” which means to make them obtuse and unresponsive. Other versions have “render the hearts of this people insensitive” (NASB), “make the heart of this people calloused” (NIV), “make the mind of this people dull” (NRSV, TEV), “make these people close-minded” (GW), and “make the minds of these people dumb” (NCV).

Plug their ears. The Heb. lit. says, “Make their ears heavy” and should be understood in a sense parallel to the “fat” hearts of the previous line. Other versions render “their ears dull” (NASB, NIV) and “stop their ears” (NRSV).

6:12 sent … away. The Heb. rakhaq [TH7368, ZH8178] means “be far away.” For this usage in contrast to “near,” see 13:5–6; 33:13; 57:19.

deserted. The Heb. ʿazab [TH5800, ZH6440] is one of a number of verbs meaning “abandon, reject, despise.” If the people reject and abandon the Lord (in favor of evil and idols), he will do the same to Israel.

6:13 stump. Heb. matsebeth [TH4678, ZH5169] (cf. HALOT 1:621); a rare word found twice in this verse and nowhere else in Isaiah. This is an important figure, used also in 11:1. Here it signifies the remnant of Israel.