The English language phrases Calm Down and Go Easy have related meanings, but they are different, as I shall explain, using British English examples.
Calm Down (verb) is an instruction to the listener to reduce their level of emotion. It is often used towards children, or adults when there is a power imbalance between the speaker (in power) and the listener.
"Calm down, children, we need to start the exercise."
"Sir, please calm down, or I will have to use the taser on you."
"Let's hope he calms down after such an exciting day."
Calm Down can also be used about objects and events rather than people.
"The water calmed down after the storm and we were able to set sail once again."
"The city calmed down quickly after the curfew was imposed."
Go Easy (verb) is an instruction to the listener to be less severe in their actions, that is, to be more gentle. In fact to "go easy" can in most situations be replaced by "go gently", including all of the following examples:
"Please go easy around this next corner, it could be icy."
"Darling, please go easy on the child, he didn't mean to break it."
"Don't go easy on me, I want to know I am up to this challenge."
The past tense is Went Easy, for example:
"The guards went easy on the protester, they secretly supported his cause."
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