Philosophy is the structured method by which one uses reason and linear logic to arrive at an understanding of the nature of things.

Philosophia means "lover of wisdom", and originally Philosophy was the Jnanan Yoga or Knowledge Path to Enlightenment of the West.  This was especially so under teachers like Parmenides, Pythagoras, Socrates, and Plato, who adopted a paradigm in which science and mysticism were not two distinct things, but rather came together as holistic vision of Reality.  Others like Thales, Democles, Empedocles, and Aristotle adopted a more scientific approach, albeit still acknowledging a certain metaphysical reality.

Yet when we look at the history of Western Philosophy we see it represents a long march from wisdom tradition to secular intellectualism.

The history of philosophy in the West stems ultimately from the twin giants of Plato and Aristotle, especially as interpreted by the Medieval theologians (Aquinus, Anselm, etc) for whom philosophy was but the handmaiden of the Church, and then the break with institutionalised religion with the 17th and 18th century post-rennaisance thinkers like the Descartes, Spinoza, Leibnitz, Berkely, and others, some of whom were also neveretheless (like Pythagoras and Plato) mathematicians or theologians.  Yet already under contemporary individuals like Hume, Hobbs, Locke and Rousseau all trace of metaphysical reality was rejected and philosophy and understanding was very much confined to mundane phenomena.

The strongly metaphysical German Idealism developed in the 18th and 19th century with great thinkers like Kant, Fichte, Schelling, and Hegel.

The 19th century also saw the rise of secular, moral, psychological, and social political philosphy, with names like J. S. Mill, Jeremy Bentham, Karl Marx, Pierce, Nietzsche, and William James.

In the 19th and 20th century also arose the two great modern currents of western philosophy:

• the Anglo-American antimetaphysical (reductionist objectivist) Analytical Philosophy (Moore, Russell, Ryle, Quinne, etc) with its early spin-off in the Linguistic Philosophy of Ludwig Wittgenstein.
• and the European subjectivist movement of Existentialism (Kierkegaard, Heidegger, Sartre, and Merleau-Ponty).

There were and are other philosophical movements - Phenomenology, Process Philosophy, etc, but these are relatively minor in influence.