Exegesis:
legōn ‘saying,’ here denoting an act to be distinguished from that to which the main verb eklausen refers.
ei egnōs en tē hēmera tautē kai su ta pros eirēnēn ‘if only you too had known, on this day, the things which make for peace,’ with no main clause following, and hence virtually equivalent to a wish which cannot be fulfilled. en tē hēmera tautē refers to the day of Jesus’ glorious entry. kai su may mean ‘even you,’ i.e. ‘you yourself,’ or, ‘you too,’ i.e. as well as the disciples, preferably the latter. ta pros eirēnēn lit. ‘the things that have to do with peace,’ hence, ‘the things that make for peace.’
nun de ekrubē apo ophthalmōn sou ‘but as it is they are hidden from your eyes.’ nun means ‘as things are now,’ ‘as it is,’ and refers to the spiritual state in which Jerusalem is. The clause as a whole may refer to inability or to prohibition, preferably the former. Subject of ekrubē is ta pros eirēnēn.
Translation:
Saying, preferably, ‘and (he) said.’
Would that even today you knew, preferably, ‘if only you too had known today.’ The sentence is often introduced by a particle or phrase with desiderative or supplicatory force, e.g. in Sundanese, Sranan Tongo. You (sing.) refers to the city of Jerusalem. Where idiom is such that one cannot address a city but only the people in it, one may have to shift to ‘you (plur.),’ or more explicitly, ‘your inhabitants.’ To know is used here in the sense of ‘to have understanding of,’ ‘to recognize the nature of.’
The things that make for peace, or, “the way that leads to peace” (New English Bible), “what is needed for peace” (Good News Translation), ‘the things which cause-to-happen peace, or, cause peace to come to you, or, assure peace’ (cf. Trukese, Shona 1966, Zarma). In languages that use distinctive terms for the positive and negative meaning of ‘peace’ (see on 1.79) the choice is difficult here. Some versions, e.g. Bahasa Indonesia RC, Batak Toba use the latter because they view the term as primarily referring to reconciliation, the end of the strife between God and his people; others (e.g. Bahasa Indonesia, Javanese) prefer the positive term (which, of course, may imply the concept of being reconciled to God). The latter is preferable, as a rule.
But now, preferably, ‘but as it is’; or bringing out the implied disappointment more strongly, “but no” (New English Bible), mais hélas (Bible de Jérusalem).
They are hid from your eyes, or, ‘they are kept from your sight,’ ‘you are unable to see/perceive these things.’
Quoted with permission from Reiling, J. and Swellengrebel, J.L. A Handbook on the Gospel of Luke. (UBS Handbook Series). New York: UBS, 1971. For this and other handbooks for translators see here . Make sure to also consult the Handbook on the Gospel of Mark for parallel or similar verses.