People also sometimes think semicolons are fancy colons. They are not. See the next item. In essays, colons are used most frequently to introduce quotations. Again, the reason the second revision works is that the words before the colon stand by themselves as an independent clause.
Dashes can act as semi-colons, connecting independent clauses.
They can take the place of colons in introducing lists. They can serve to insert an example, and allow you gracefully to get back to the main sentence. In Coriolanus , Sicinius and Brutus are the tribunes of the people-the voice of the people. Any word processor can produce a dash. However you produce it, don't put spaces on either side of the dash.