A scheme is a plan or arrangement involving many people which is made by a government or other organization.

A scheme is someone's plan for achieving something.

If you say that people are scheming, you mean that they are making secret plans in order to gain something for themselves.

Someone's scheme of things is the way in which they think that things in their life should be organized.

When people talk about the scheme of things or the grand scheme of things , they are referring to the way that everything in the world seems to be organized.