Your thesis is the keystone of your essay: everything builds toward it, and without it everything falls apart. Your reader should be able to read your single sentence thesis and understand (in broad terms) what your essay is about.
Broadly speaking, a thesis should have two different pieces: context framing, and presentation of your arguments. The context framing sets up the sentence so that it can introduce the arguments, and it makes specific reference to the text (or texts) you'll be citing in your essay. The presentation of your arguments provides a list of the core ideas in each of your topic sentences. Here's an example thesis that we'll be working with on this page:
The actions of Atticus Finch prove that humility will create influence over people who would otherwise be uninterested, intelligence inspires respect from a community, but idealism can cloud a person’s judgment.
(This thesis would work for a character analysis essay on Atticus finch, where the each body paragraph focuses on a trait held by the character, and explores the lesson or insight that the reader can gain about the trait from that character.
This part of the thesis is relatively simple. All it has to do is set up the sentence so that you can finish the rest of it with a list of your arguments, and name drop your subject from the text. (NOTE: you do not need to mention the author or title in the thesis, as that should be covered by another sentence in your introduction paragraph.
From the example above, this is the context framing: "The actions of Atticus Finch prove that"
Notice that this is not even a complete thought: it needs to have at least one of the arguments to complete the sentence. This is usually a good thing to keep in mind: without the arguments, your thesis should feel incomplete. This is one of the reasons that it's sometimes best to write your context framing after you have written the presentation of your arguments. See the last section below for more explanation.
This part of your thesis summarizes each of the arguments that you're going to make in your topic sentences and presents them in a list. To do this, it's helpful to look at each topic sentence, identify the core argument, trim out everything else, and condense the language down into as short a phrase as possible.
From the example above, this is the presentation of arguments: "humility will create influence over people who would otherwise be uninterested, intelligence inspires respect from a community, but idealism can cloud a person’s judgment"
Notice that this is actually three separate ideas, presented in list form:
humility will create influence over people who would otherwise be uninterested
intelligence inspires respect from a community
idealism can cloud a person’s judgment
Here's a breakdown of how we were able to arrive at those phrases. We'll start with the topic sentence from the first argument:
When a humble person, like Atticus, can keep his or her pride from offending other people, they are more likely to listen and be influenced by that person’s thoughts because those listening are less likely to be bothered by the speaker’s arrogance.
This can be shortened simply to "humility will create influence over people who would otherwise be uninterested." Cutttng the reasoning and context is the first step to shortening a topic sentence in this way, as the reasoning can wait until the body paragraph, and the context will already be established in the thesis by the context framing (so it's pointless to establish the context twice in one sentence).
Keeping the core argument and shortening it to the fewest words possible (without loosing the main focus) can be accomplished without cutting the significance, if you are able to keep your wording focused on the broad idea rather than a specific character or textual feature.
Here are the other examples from the thesis above. The second topic sentence looks like this:
Atticus’ intelligence proves that the ability to consider a problem from several perspectives, or analyze a dilemma from a sophisticated point of view causes a community to rely on their most intelligent members for problem solving, and that person earns respect of the people around him or her as a result.
Which can be condensed to:
intelligence inspires respect from a community
Finally, the third topic sentence reads:
Atticus’ absolute devotion to the ideal of justice prevents him from seeing the people around him on a human level, because upholding justice becomes more important to him than maintaining healthy relationships with his friends and family.
Which can be shortened to:
idealism can cloud a person’s judgment
Write your thesis in reverse order. Start by summarizing the arguments in your topic sentence, and arranging them in a list. After that, you can compose context framing to start a sentence that will end with your list.
Keep your arguments in order. The order in which your introduce your arguments should be the same order that they appear in your essay.
Keep it at one sentence. Part of the challenge of writing a good thesis is to constrain it to one sentence. Brush up on your grammar if you need to remember how to include several phrases in one sentence.