When Hooper visits Brody's home, he brings two bottles of wine. Brody pours himself a large measure, and then gives his wife and Hooper some. If you look at the bottle, firstly it seems rather full for the amount he's just poured, and secondly the level changes from shot to shot. Sometimes it's above the label, sometimes below.
The purpose of an Essay Introduction is to introduce the reader to the subject matter you are writing about and to state the intent of the paper.
The purpose of an essay is to encourage students to develop ideas and concepts in their writing with the direction of little more than their own thoughts (it may be helpful to view the essay as the converse of a research paper). Therefore, essays are (by nature) concise and require clarity in purpose and direction.