How do the seven Seals work as a table of contents for Revelation?

The book in God's hand had writing on the inside and on the outside. The seven seals covered the outside writing, and that outside writing functioned as a table of contents, summarizing the key themes and elements that would be found once the book was actually opened. The seals themselves do not cause anything to happen; they simply announce or list what is contained within the book. When the Lamb opens each seal, John is not watching events unfold on earth in real time. He is watching a visual representation of concealed writing being revealed to him, seeing rather than hearing what was written.

Each seal, when opened, discloses either a major agent, a major theme, or a foreshadowing of major events that will appear later once the book is opened and read from Revelation 8 onward. Seal one reveals the white horse rider as an agent whose power and influence will be seen at work later in the book. Seal two reveals the red horse rider, preparing the reader for the recurring theme of war. Seal three reveals the black horse rider, preparing the reader for themes of famine and economic pressure. Seal four reveals two agents, Death and Hell, preparing the reader for widespread death and the release of forces from hell. Seal five previews the theme of violence and martyrdom concerning the saints. Seal six gathers up nearly every major outcome of the book into one sweeping vision, including judgment on the wicked, deliverance of the righteous, the wrath of God, Christ reigning, and God dwelling with His people, along with the sealing of the 144,000, which also gives a chronological marker showing that the trumpets cannot begin until that sealing is complete. Seal seven concealed no writing at all; it was simply the final seal keeping the book shut, and once it was removed, the book itself could finally be opened.

In this way, Revelation chapters six and seven cover the entirety of the outside writing of the book, giving the reader a preview of what is coming, while the inside writing, found in Revelation eight through twenty two, is what actually reveals the prophetic timeline in detail, sequence, and execution. The seals are already opened, and the outside writing has already served its purpose of pointing forward. What remains is the unfolding of what is written inside the book, beginning with the sounding of the trumpets.