Isaiah 40:4

כָּל-גֶּיא יִנָּשֵׂא וְכָל-הַר וְגִבְעָה יִשְׁפָּלוּ וְהָיָה הֶעָקֹב לְמִישׁוֹר וְהָרְכָסִים לְבִקְעָה

4 Every valley will be raised up and every mountain and hill will be made low. The rough ground will be level and the rugged places a plain.

כָּל-גֶּיא יִנָּשֵׂא  every valley will be raised up, יִנָּשֵׂא is a nifal imperfect (notice the classic nifal imperfect ih-ah-ey vowel pattern, with dagesh forte in the second radical). Students of Hebrew searching for ways to memorize vocables (root words) often remember that the root נָשָׂא "lift up" sounds like NASA, which lifts up rockets. Although there is no qere, the editors would have us read the hapax גֶּיא "valley" as גַיְא. Isaiah consistently retains an e-vowel in this word (גֵּיא) throughout the book: Isaiah 22:1; 28:1; 28:4; 40:4, as does Jeremiah (7:32; 19:6), but see Gesenius 93v on this construct form.

וְכָל-הַר וְגִבְעָה יִשְׁפָּלוּ  and every mountain and hill will be made low. The word for "hill" is the root of the name Gibeah (Judges 19:12). The verb "be made low" (qal imperfect 3 m pl) is also the root of the noun shephelah, the "foothills" that formed the buffer between the plains and the higher mountains (Deuteronomy 1:7; Obadiah 19; Zechariah 7:7, etc.).

וְהָיָה הֶעָקֹב לְמִישׁוֹר  The rough ground will be level, Since וְהָיָה is a vav-consecutive perfect, it continues the effect of the imperfect verbs that have gone before. עָקֹב here means "bumpy, uneven." This is a root that normally means "heel, footprints" or that can even be the conjunction "because," but the meaning here is supported by the LXX (σκoλιά, "crooked," cp. scoliosis). In Ethiopic, a very similar root, aqob means "sloping ground," which would fit the context here, and the Syriac translation uses armah, equivalent to the Hebrew  עֲרֵמה "heap, pile of ruins" (2 Chron. 31:6). מִישׁוֹר is a noun, "a level place," (cp. Isaiah 42:6); the lamed is used here "to introduce the result after a verb of making, forming, changing" (GK 119t, page 381).

וְהָרְכָסִים לְבִקְעָה  and the rugged places a plain. Obviously הָרְכָסִים is parallel to "rough ground" above, but the word is hapax and "rugged places" is just a good guess. בִקְעָה "plain" is the same word as in Genesis 11:2, the "plain in Shinar." Once again the lamed introduces the result of the change, and no verb is necessary since these words are in synonymous parallelism with the preceding clause.

All obstacles will be cleared away, including our own impenitent hearts. Remember that Jesus "could not do many miracles there (in Nazareth) because of their unbelief" (Matthew 13:58).