The Source is the ninth studio album from Ayreon, a progressive metal/rock opera project by Dutch musician Arjen Anthony Lucassen, released on 28 April 2017.

In the typical style of the project, the album features several guest singers to portray the characters across the album; although Lucassen usually prefers to work only once with each singer in Ayreon, he mostly cast returning performers for The Source, including James LaBrie (Dream Theater), Simone Simons (Epica), Floor Jansen (Nightwish), Hansi Kürsch (Blind Guardian), Tobias Sammet (Edguy, Avantasia), Tommy Karevik (Kamelot, Seventh Wonder), and Russell Allen (Symphony X), together with newcomers such as Tommy Rogers (Between the Buried and Me), for a total of eleven main vocalists.

[1][4] The Source is set before all previous albums, and tells the origins of the Forever, an alien race central to the Ayreon storyline.

[1] The story begins in the distant past on a planet called Alpha in the Andromeda Galaxy, inhabited by our human ancestors.

Despite the best efforts of The Opposition Leader (Tommy Karevik), The President (Russell Allen) has given a mainframe computer known as "The 'Frame" full powers over Alpha, so it can solve its seemingly insurmountable ecological and political problems.

Some Alphans, such as The Diplomat (Michael Eriksen) and The Counselor (Simone Simons), believe there is still hope, as does The Captain (Tobias Sammet), who proposes to use his spaceship, the Starblade, to carry a small number of Alphans to a new world so they can start anew; meanwhile, The Prophet (Nils K. Rue) foresees that they will indeed leave, while also predicting "a sea of machines" similar to Alpha's and a mysterious castle ("Sea of Machines").

After finally escaping from Alpha, the surviving humans are injected with a drug made by The Chemist (Tommy Rogers), named "Liquid Eternity" but mostly referred to as "The Source", that will make their bodies able to live underwater and communicate by telepathy, as the world they are going to is an aquatic one; it will also drastically extend their lifespans, making them virtually immortal.

The former Alphans ultimately awaken as they reach Sirrah and mourn, aware that during the many years it took them to travel, their planet, together with all their loved ones, has come to an end ("Deathcry of a Race").

[3] Drummer Ed Warby, violinist Ben Mathot, and flutist Jeroen Goossens, all longtime Ayreon collaborators, returned for the album.

[3] In August 2018, Lucassen stated that he had asked Andrew Latimer of Camel, one of his "top five favorite guitarists of all time", to be in the album.

[10] "The Day That the World Breaks Down", the opening song of the album which features all the cast except Zaher Zorgati, was released by Lucassen on YouTube on 26 January 2017.

Sputnikmusic gave a rating of 3.5 out of 5, stating: "With The Source, Arjen continues to fully realize his conceptual ideas, although when piecing together the obviously stronger tracks, it seems a double album may not have been so necessary in the end" .

[22] Maximum Volume Music gave a perfect 10 rating and stated "whilst April is too early to proclaim a record as the best of 2017, what we will say is this: anything that ends up being better than “The Source” is going to have to be extremely special, because this is truly magnificent".

[18] Myglobalmind gave a perfect 10 rating, stating "The Source is yet another outstanding rock opera that once again proves Arjen Lucassen’s ability to tell a compelling story, while still giving his fans memorable songs and some excellent instrumental work, to go along with a truly impressive cast of singers".