The term 'sum and substance' is a phrase used to describe the GIST or ESSENCE of something. It is often used to refer to the most important points of a discussion or argument. GIST, with four letters, is an acronym for 'General Idea Summary Technique, ' which is a method of summarizing information. ESSENCE, with seven letters, is defined as the intrinsic nature or indispensable quality of something, especially something abstract. Together, these two words can be used to describe the most important points of a discussion or argument.