~ものだ
Describe what is naturally expected or generally true
You’ll be able to state a general norm, tendency, or piece of conventional wisdom.

山を歩くと、疲れるものです。
yama o aruku to, tsukareru mono desu.
What do you think this sentence means?
When you walk in the mountains, you naturally get tired.
Express general truths and natural tendencies
~ものだ states a general truth, natural human tendency, or common expectation ("it is natural that...", "people generally..."). It does not describe a single specific past event.
子どもはよく笑うものだ。
kodomo wa yoku warau mono da.
Children laugh a lot; that’s just how they are.
楽しい時間はすぐに過ぎるものだ。
tanoshii jikan wa sugu ni sugiru mono da.
Good times always pass quickly; that’s just how it is.
Attach ものだ to plain present forms
Attach ものだ to plain present forms (dictionary or negative forms) of verbs and adjectives to express inherent nature or how things naturally are.
薬は苦いものだ。
kusuri wa nigai mono da.
Medicine is naturally bitter.
忙しいときほど、部屋は散らかるものだ。
isogashii toki hodo, heya wa chirakaru mono da.
The busier you are, the messier your room tends to get.
「新しい町にまだ慣れなくて…」「引っ越したばかりのころは、だれでも寂しくなるものですよ。」
“atarashii machi ni mada narenakute…” “hikkoshita bakari no koro wa, dare demo sabishiku naru mono desu yo.”
“I’m still not used to the new town…” “Right after you move, everyone gets a little lonely.”
他人の間違いはすぐ見つかるのに、自分の間違いにはなかなか気づかないものだ。
tanin no machigai wa sugu mitsukaru noni, jibun no machigai ni wa nakanaka kizukanai mono da.
We spot other people’s mistakes right away, yet we rarely notice our own.
7 more examples in the grammar path — free for a limited time.