関武夫さんという自然を愛している方が生前持っていた森を、ご遺族の方が（財）埼玉県生態系保護協会に寄付したんですね。 Intuitively, The natural amount n will be the typical house of all sets that have n components. So, it seems natural to define n as an equivalence class under the relation "could be built in a single to 1 correspondence". get - acquire by trade or sacrifice or Trade; https://www.slideshare.net/slideshow/stay-fit-with-cureayu-natural-health-products-india/282503834