Ethics, Demonstrated in Geometrical Order(or simply Ethics) is a philosophical treatise originally written in Latin by Baruch de Spinoza. It was written between 1661 to 1675, only being published after his death in 1677. As an application of Euclid's method used in The Elements, the book is an exercise in a logic from defining the nature of God and the relations of God with the universe, through the human mind and body, the underlying striving towards the ever-lasting of being, the human passions, to the aid of reason as a form of liberation from the mediated "sad passions" of humans in their place in the natural order, towards the path of attainable happiness.

Ethics centers around a particular metaphysical proposition, of God, or Nature, (Deus sive Natura) as the only true substance, and all which we experience are only particular modulations experienced in extension (matter) or thought(mind). From this metaphysical pinpoint, it can be understood that the entirety of extension and thought comprise of the entire system of the universe, and through the entirety of processing the mind is the Absolutely Infinite Understanding. In the logical deduction of Being, in clarifying Nature, Spinoza believes that the process of reasoning and philosophy can shed us of our confusions, and propel us towards perceiving ourselves from the perfection of God/Nature. Through this process of a kind of immanent becoming through philosophy, Spinoza believes that our peace and unity with the Divine is one(or perhaps won, depending upon how you will read this book) in "True Blessedness".