Here’s a New Year’s Resolution for you!
(Ichinichi no kei wa asa ni ari ichinen no kei wa gantan ni ari;
“A day’s plan in the morning; a year’s plan on New Year’s Day”)
Planning and preparation should be done well in advance of when they are needed. A year’s plans should be made on the first day of the year. If you only decide how to do a thing as you’re doing it, your work often becomes slapdash and haphazard; it’s better to be ready before the work itself begins if you want your work to go well. The beginning is the most important part of any undertaking.
This is a pairing of parallel structures. We will begin with the first one, examined from right to left.
Our governing verb is 在り (ari), “to be.” The particle に (ni), here acting as a positional marker, connects the verb to the noun 朝 (asa), “morning.” The topic marker は (wa) tells us that the rest of the clause will be a single noun phrase describing what is situated in the morning. The primary noun of this phrase is 計 (kei), “plan.” The associative particle の (no) tells us what kind of plan it is by attaching it to the number-noun combination 一日(ichinichi), “one day.”
The latter half is identical except for replacing “day” with 年 (nen, when you count them), “year,” and “morning” with 元旦 (gantan), the first day of the new year (or even specifically the morning of that first day).
Either half of this kotowaza may be used on its own. In fact, at first I was only aware of the latter half, about the year; the former half was found and added in the course of researching this post.
計 may be pronounced hakarigoto, and 朝 may be pronounced ashita, without any change in meaning. I suspect that the feeling given by using these pronunciations is more old-fashioned or poetic; they are not standard in modern Japanese. The original version of this saying, apparently from a sort of almanac called the 月令広義 (Getsu.ryou.kou.gi), used the character 晨 (ashita), “morning” in place of 朝 and 春 (haru), “spring,” in place of anything explicitly indicating the new year. Keep in mind though that in the old Chinese-style calendar, the first day of the year occurred in February or so and marked the beginning of the spring season.
On the other hand, 元旦 may be replaced with 元日(ganjitsu), “the first day of the year” or 正月 (shougatsu), “the first month / the first three days / the first day – of the new year,” without any significant change in feel.
(“Ichinen no kei wa gantan ni ari kara to iwan bakari ni, Keiji ga migoto de fukuzatsu na shinnen no houfu no keikaku wo tateta.”)
[“Keiji developed a marvelous, complicated strategy for his New Year’s resolutions, as if to say that a year’s plan belongs on its first day.”]