"The author knows just what he wants to illustrate and how he would like it to be done"

This quote by Louis Leakey suggests that the author has a clear vision of what they want to communicate and how they wish to do it. It indicates that the author has a strong sense of function and instructions, and is positive in their capability to effectively interact their message. It also recommends that the author is arranged and has a prepare for how they wish to present their ideas. This could mean that the author has made the effort to carefully consider their method and has thought through the very best method to illustrate their point. Eventually, this quote indicates that the author is well-prepared and has a clear concept of what they wish to accomplish.