John Tukey‘s wisdom on importance and value of graphics and pictures in making sense of exploring data.
Consistent with this view, we believe, is a clear demand that pictures based on exploration of data should force their messages upon us. Pictures that emphasize what we already know — “security blankets” to reassure us — are frequently not worth the space they take. Pictures that have to be gone over with a reading glass to see the main point are wasteful of time and inadequate of effect. The greatest value of a picture is when it forces us to notice what we never expected to see. (p. vi emphasis in original)
John Tukey – Exploratory Data Analysis