"explanatory conditions & factors"
The 4 causes:
| Causal matrix | surface | underlying | 
| formal | final, or teleological | |
| material | efficient | 
Aristotle, Physics, (350 BCE.).
formal
 What is a characteristic of real things?
 the apparent property or external quality displayed;
 an actual shape, texture, extension, hue, appearance. A pattern taken or given by things in our sensory experience.
 quartz crystals have a geometrical shape
 water molecules have an hexagonal appearance
 marble has a sinuous quality
 form and matter exist concurrently in all things
 marble in the statue of Michelangelo's "David."
 matter represents the unchanging consistency beneath the changing form. i.e.
 caterpillars metamorphose into a butterflies
 crabs molt and shed their shells (carapace)
 snakes shed their skin
 tadpoles develop into frogs
 warmth & moisture
  efficient
  that which moves matter and form to undergo visible changes:
 the sculptor of a statue or creator of an art work
 cold air that turns the leaves of deciduous trees from green
 molten lava that cools into igneous rock
 rain water forming carbonic acid that breaks down rocks
 hormones that release eggs from a mammal's ovaries
  elements that remain behind after the alteration are 
  clues
  
 purpose, end, or aim
 orderly universe, with ordered certainty things develop toward ends determined by their natures
 apprehended by human reason (experience & rationality) sensible qualities are the building blocks of reality whose purpose is to strive to attain the "good" or optimal character
 the all pervading character of the unstable conditions

4 causes: formal | material | efficient | teleology