Monism is a philosophical belief that there is only one causal principle at work in the universe. This principle is often referred to as the 'ultimate reality' or the 'absolute truth'. Monism is closely related to other philosophical concepts such as pantheism, which holds that all of reality is part of a single divine being, and dualism, which holds that there are two distinct principles at work in the universe. Monism is often seen as a more holistic approach to understanding the world, as it seeks to explain the interconnectedness of all things.