I'm having some trouble with this beautiful passage from the Kana Preface to the Kokinshū, which is talking about us (spaced for clarity):
1 人まろ なくなりにたれど、
2 うたの こと ゝどまれるかな。
3. たとひ とき うつり こと さり、
4. たのしび かなしび ゆきかふとも、
5. この うたの もじ あるをや。
6. あをやぎの いと たえず、
7. まつの はの ちりうせず して、
8. まさきのかづら ながく つたはり、
9. とりのあと ひさしく とどまれらば、
10. うたの さまを(も) しり、
11. ことの こゝろを えたらむ人は、
12. おほぞらの 月を みるがごとくに、
13. いにしへを あふぎて いまを こひざらめかも。
The Iwanami and Shogakukan anotated editions tell us two pieces of cultural context needed to understand it:
- The modifier clauses starting each line in 6-9 are traditional images (序詞) for the things that follow: green willow threads for "not ceasing", pine needles for "not scattering", the masaki-no-kazura vine for "reaching long", and bird tracks for "lasting a long time". It may seem strange that bird tracks would be an image for 久しく とどまる, but this is due to the fact that:
- 鳥の跡 is a conventional metaphor for "written characters" (due to the legend that Cangjie invented characters by imitating the footprints of plovers). So this particular image also echoes the point of line 5 above.
(grammar note: if とどまれらば seems weird, it's because ら here is the 未然形 of the perfective/progressive suffix, り.)
Now here's Lamarre's translation:
Although Hitomaro has gone, the acts of songs have remained. Even though eras shift and deeds pass, and delights and sorrows come and go, the characters (moji) of songs continue. Should they be retained as changeless as birdtracks and transmitted as long as rampant vines, just as the evergreen needles never scatter and vanish, just as the threads of green willows always trail, then the people who know the designs of songs and obtain the hearts of words surely will look up to the high ages and yearn for this day, just as we look to the moon in the great heavens. [emphasis mine]
A bit liberal in some aspects, and it glosses over the "bird tracks=characters" motif, but my question is regarding the parts in bold. I don't see how we came from the morphology and syntax of 6-9 to an interpretation where:
- The moji or uta of the previous sentence ("they") is supposed to be the subject of the conditional (todomareraba), and
- The 4 images (aoyagi, matsu-no-ha, masaki-no-kazura, tori no ato) are targets for the condition: "if they last as long as the bird tracks"… (and not, as I'd expect from the isolated clause: "if the bird tracks last long"…)
I've checked the modern translations/explanations in Iwanami and Shogakukan, and also the Portuguese one by Wakisaka, and they all agree on this point; e.g. Shogakukan:
この歌が青柳の糸の絶えぬごとく[…]鳥の跡の久しく残ることくに、長く後世に伝わりますならば […]
But I'm not used to Classical, so I don't understand where are the ごとくs coming from…
TL;DR: In the first citation above, why does 鳥の跡久しくとどまれらば translate to "if the poems last as long as the bird tracks" and not just "if the bird tracks last long"?