A "Materialist" is someone who believes that physical matter is the primary substance of reality. This perspective emphasizes that everything, including thoughts and feelings, can be explained through material interactions. Materialists often reject spiritual or supernatural explanations, focusing instead on observable phenomena. In philosophy, materialism contrasts with idealism, which posits that reality is fundamentally mental or spiritual. Prominent materialist thinkers include Karl Marx and Friedrich Engels, who applied materialist principles to social and economic theories. In everyday life, materialism can also refer to a preoccupation with material possessions and wealth, often prioritizing physical goods over emotional or spiritual fulfillment.