Japatan
Formation
- V辞書形 + ものだ
- Vない形 + ないものだ
- いA + ものだ
- なA + な + ものだ
- Vた形 + ものだ(昔のことを思い出す)
Explanation
There are three main uses. (1) A general truth about the nature of people or things: "that's just how it is." (2) What one should do by common sense; the negative is 〜ないものだ. (3) With the ta-form, remembering with nostalgia something you often did in the past, often with よく or 子どものころは.
Examples
新しい仕事は、最初はだれでも大変なものだ。
A new job is hard for anyone at first.
楽しい時間は、すぐに過ぎてしまうものだ。
Fun times always pass quickly.
約束の時間は守るものだ。
You should keep to the time you promised.
学生のころは、よく友だちと朝まで話したものだ。
When I was a student, I often used to talk with my friends until morning.
Notes
Use (2) is close to 〜べきだ, but ものだ presents it as common sense in society. Use (3) is for repeated past habits, not a single event (not 去年一度京都へ行ったものだ).
Related grammar
Mini quiz
1小さいころは、この川でよく泳いだ（ ）。
Answer and explanation
Answer: 3 ものだ
"When I was little, I often used to swim in this river." With 小さいころは and よく, ta-form + ものだ expresses a nostalgic past habit. The other choices cannot express this meaning.
2電車の中では、大きな声で（ ）ものだ。
Answer and explanation
Answer: 1 話さない
"You shouldn't talk loudly on the train." Common-sense advice in the negative is the nai-form (〜ない) + ものだ. The other forms do not connect to ものだ.
3初めての場所では、だれでも（ ）ものだ。
Answer and explanation
Answer: 4 緊張する
"Anyone gets nervous in a new place." ものだ for a general truth follows the dictionary form 緊張する. 緊張 is a noun, so 緊張な or 緊張の is wrong here.
