I do not think that this statement is literally true, in the sense that giving your all to something is not exactly "satisfying" while the experience of knowing you did your best can occasionally give you a boost, the true satisfaction is not about how much effort you gave, but about overcoming the difficulty. Whether you give 59% or 120% to a task, overcoming something that was difficult is always satisfying.
Radiocarbon dating hope this helps
Feudalism was the system of rule during the medieval period. The liege lord granted land to a vassal in exchange for service and an oath of fealty. ... Additionally, feudal contractswere agreed upon in exchange for things other than military service, including produce, protection and salary.
Early democratic actions in the Americas
The 15th amendment, which was about not disallowing anyone to vote based on their color