ADJ in n
The 'safe' group
These adjectives indicate that someone has a feeling about something. The noun group following the preposition in indicates the cause or scope of that feeling.
I was confident in my ability to play the game again after a 10-year lapse.
I feel very disappointed in him and very let down.
He was happy in his Apache life and more fulfilled than he'd ever been.
In the case of comfortable, confident, and happy the preposition in is sometimes followed by an '-ing' clause.
comfortable confident disappointed frozen happy miserable nervous unhappy
If as a child you feel loved, you are most likely to feel comfortable in expressing your feelings.
The adjectives listed below are used with the phrase in the knowledge and indicate that someone feels safe or comfortable because they know something.
Safe in the knowledge that your pets are enjoying their holidays, you can relax and enjoy yours.
The adjective easy is used with the verb rest.
certain comfortable confident content easy happy safe secure smug sure
The person who misses out can rest easy in the knowledge that he will be a part of our campaign for the rest of the year.