What document serves as a guide for amending the Illinois Constitution?

The Illinois Constitution itself serves as the guide for amending the Illinois Constitution. Within its text, the document explicitly outlines the procedures and requirements that must be followed for amendments to be proposed and ratified. This internal governance structure ensures that any changes to the Constitution are carried out in a systematic and orderly manner, reflecting the will of the people and the principles of democracy.

In contrast, the other options do not provide a framework for amending the Illinois Constitution. The United States Constitution, while informative regarding federal amendments, does not directly govern state constitutions. The State Legislative Manual provides information on legislative procedures but is not designed specifically for constitutional amendments. The Declaration of Independence, while a foundational document in American history, does not contain provisions related to constitutional amendment processes. Thus, the Illinois Constitution itself is the appropriate and authoritative source to reference for amendments to its content.