Plato argued that all things have a universal form, which could be either a property or a relation to other things
When one looks at an apple, for example, one sees an apple, and one can also analyse a form of an apple
In this distinction, there is a particular apple and a universal form of an apple
Moreover, one can place an apple next to a book, so that one can speak of both the book and apple as being next to each other
Plato argued that there are some universal forms that are not a part of particular things
For example, it is possible that there is no particular good in existence, but "good" is still a proper universal form
Aristotle disagreed with Plato on this point, arguing that all universals are instantiated at some period of time, and that there are no universals that are unattached to existing things
In addition, Aristotle disagreed with Plato about the location of universals
Where Plato spoke of the forms as existing separately from the things that participate in them, Aristotle maintained that universals exist within each thing on which each universal is predicated
So, according to Aristotle, the form of apple exists within each apple, rather than in the world of the forms
Coming-to-be is a change where the substrate of the thing that has undergone the change has itself changed
In that particular change he introduces the concept of potentiality (dynamis) and actuality (entelecheia) in association with the matter and the form
Referring to potentiality, this is what a thing is capable of doing or being acted upon if the conditions are right and it is not prevented by something else
For example, the seed of a plant in the soil is potentially (dynamei) a plant, and if it is not prevented by something, it will become a plant
Potentially beings can either 'act' (poiein) or 'be acted upon' (paschein), which can be either innate or learned
For example, the eyes possess the potentiality of sight (innate – being acted upon), while the capability of playing the flute can be possessed by learning (exercise – acting)
Actuality is the fulfilment of the end of the potentiality
Because the end (telos) is the principle of every change, and potentiality exists for the sake of the end, actuality, accordingly, is the end
Referring then to the previous example, it can be said that an actuality is when a plant does one of the activities that plants do
In summary, the matter used to make a house has potentiality to be a house and both the activity of building and the form of the final house are actualities, which is also a final cause or end
Then Aristotle proceeds and concludes that the actuality is prior to potentiality in formula, in time and in substantiality
With this definition of the particular substance (i.e., matter and form), Aristotle tries to solve the problem of the unity of the beings, for example, "what is it that makes a man one"
Since, according to Plato there are two Ideas: animal and biped, how then is man a unity
However, according to Aristotle, the potential being (matter) and the actual one (form) are one and the same
Aristotle uses induction from examples alongside deduction, whereas Plato relies on deduction from a priori principles
Natural philosophy 
Aristotle's "natural philosophy" spans a wide range of natural phenomena including those now covered by physics, biology and other natural sciences
Aristotle's work encompassed virtually all facets of intellectual inquiry
Aristotle makes philosophy in the broad sense coextensive with reasoning, which he also would describe as "science"
However, his use of the term science carries a different meaning than that covered by the term "scientific method"
For Aristotle, "all science (dianoia) is either practical, poetical or theoretical" (Metaphysics 1025b25)
His practical science includes ethics and politics; his poetical science means the study of fine arts including poetry; his theoretical science covers physics, mathematics and metaphysics
In the Empedoclean scheme, all matter was made of the four elements, in differing proportions
Aristotle's scheme added the heavenly aether, the divine substance of the heavenly spheres, stars and planets
In violent motion, as soon as the agent stops causing it, the motion stops also: in other words, the natural state of an object is to be at rest, since Aristotle does not address friction
With this understanding, it can be observed that, as Aristotle stated, heavy objects (on the ground, say) require more force to make them move; and objects pushed with greater force move faster
This would imply the equation

 ,

incorrect in modern physics
Opinions have varied on whether Aristotle intended to state quantitative laws
Henri Carteron held the "extreme view" that Aristotle's concept of force was basically qualitative, but other authors reject this
Aristotle's writings on motion remained influential until the Early Modern period
In this system, heavy bodies in steady fall indeed travel faster than light ones (whether friction is ignored, or not), and they do fall more slowly in a denser medium
Four causes 

Aristotle suggested that the reason for anything coming about can be attributed to four different types of simultaneously active factors
Material cause describes the material out of which something is composed
Thus the material cause of a table is wood
It does not mean that one domino knocks over another domino
The formal cause is its form, i.e., the arrangement of that matter
It tells one what a thing is, that a thing is determined by the definition, form, pattern, essence, whole, synthesis or archetype
It embraces the account of causes in terms of fundamental principles or general laws, as the whole (i.e., macrostructure) is the cause of its parts, a relationship known as the whole-part causation
Plainly put, the formal cause is the idea in the mind of the sculptor that brings the sculpture into being
A simple example of the formal cause is the mental image or idea that allows an artist, architect, or engineer to create a drawing
The efficient cause is "the primary source", or that from which the change under consideration proceeds