(Ashita wa ashita no kaze ga fuku;
“Tomorrow, tomorrow’s wind will blow.”)
Things might be bad today, but tomorrow could well be better, so don’t let it get you in a funk. Alternately: you don’t know what the future may hold, so helpless anxiety on the assumption that it will be bad doesn’t do you any good. In either case – whatever will be, will be, and it doesn’t do you any good to just sit and worry.
This is not a happy-go-lucky declaration that we should assume the best and let the chips fall where they may, of course. It’s still good to plan ahead and prepare for what may come. The point is rather that fretting or pessimistic rumination are also harmful.
We begin with the noun 明日 (ashita), “tomorrow,” marked as the topic of discussion by the particle は (wa). The comment on this topic begins with another 明日, marked by the associative particle の (no) as connected to and modifying the noun 風 (kaze), “wind.” This is marked by the particle が (ga) as the subject of the verb 吹く (fuku), “to blow,” which appears in conclusive form.
明日 may also be read as asu without any change in meaning. This phrase is close to, or synonymous with, a number of other phrases, including one asserting that events tomorrow will be protected by tomorrow’s gods, presumably different entities from the gods influencing today: 明日は明日の神が守る (ashita wa ashita no kami ga mamoru).
(“Kyou wa nebou shichatte iroiro umaku ikanakatta karatte, sono mama ashita mo dame ni nacchau kamo nante omoikonja dame da yo. Ashita wa ashita no kaze ga fuku sa.”)
[“Don’t fool yourself into thinking that just because you slept in today and a bunch of stuff got messed up, that things will go on being messed up tomorrow. It’s a new day, after all.”]