Picture two working tools laid across each other: a hammer, the tool of someone in a factory, and a sickle, the curved blade of someone in a field. Put one over the other on a red ground and you have a single mark that says these two kinds of workers belong together. Every use of the phrase starts from that crossed pair — the mark itself, then the flag it was printed on, then the system that flew the flag.
The supplied source says the design was made by Yevgeny Kamzolkin in 1917, built on earlier pairs such as the hammer and pick of mining, with the hammer for factory workers and the sickle for farm workers. That reading is exactly what the crossed image still shows.
本批資料所附的說明指出，這個圖案由 Yevgeny Kamzolkin 在 1917 年設計，參考了更早的「錘子與鎬」（採礦象徵）；錘子代表工人，鐮刀代表農人。今天看這個交叉的圖案，看到的仍然是同一件事。
Wiktionary entry supplied in this packet: etymology_text on 'hammer and sickle' (source_ref kaikki:3f6f69a190036ae4:732315200)
Two branches
記號本身
這一層就是畫面本身：被畫出來、刻出來、印出來的那個交叉圖案。
noun · B2
A sign showing a hammer lying across a sickle, which is a curved knife for cutting crops. It is usually drawn on a red background, and it was used to stand for communism and for the Soviet Union.
錘子與鐮刀（標誌）
記號代表的東西：那面旗，還有旗底下的制度
英文很習慣用一個記號去指它所在的東西，再指那東西背後的整件事。這兩層就是沿著這條路一步一步走出去的，起點都還是那個交叉的圖案。
noun · B2
The flag of the former Soviet Union, which carried this sign on a red background. Here the words name the whole flag, not just the mark printed on it.
蘇聯國旗