Prima Via: The Argument from Change: Change is everywhere. Someone causes it---so there must be a God like Aristotle’s “Unmoved Mover.”
Secunda Via: The Argument form Causation: Who causes causes? Is there a first cause, itself uncaused? There is. God is the original Uncaused Cause.
Tertia Via: The Argument from Contingency: How do we account for contingency in nature? Only by a Necessary Being beyond contingency.
Quarta Via: The Argument from Degrees of Excellence: We notice degrees of excellence in nature. This implies the notion of perfection, which in turn implies what we might call a Perfect Being.
Quinta Via: The Argument form Harmony: Everywhere we look is “adaptation” or “accord.” Fish need to swim so they have fins and tails. Dogs need to chew bones so they have strong teeth. These are evidence of design—the manifestation (evidence/existence) of an Intelligence that organizes things.
Francisco de Zurbarán, The Apotheosis of Saint Thomas Aquinas (1631)
St. Thomas expounds
Church Doctors review with care
This is a nice day
(Attribution: my summary of the Quinque viae is from old notes, and I take they had been borrowed and paraphrased from various sources, long since forgotten.)