From Longman Dictionary of Contemporary Englishbe at one with somebody/somethingbe at one with somebody/somethinga) CALMto feel very calm or relaxed in the situation or environment you are in She felt as she always did in these mountains: peaceful, without care, at one with nature. b) AGREE formal to agree with someone about something He was at one with Wheatley on the need to abandon free trade. → one
Examples from the Corpus
at one with nature• Being at one with nature, I decided to see one of these creatures for myself. 