UNDERSTANDING METAPHYSICS.

Metaphysics is the investigation of the fundamental nature of being and the World that encompasses it. Topics of investigation include 'existence,' 'objects and their properties,' 'space and time,' 'cause and effect,' and 'possibility.'
The investigation concerning entities that exist or may be said to exist and how they are grouped within a hierarchy is called Ontology.
Parmenides (5th BC) was a pre-Socratic Greek philosopher from Elea in Great Greece (name given by Romans to Coastal areas  of Southern Italy). He was the founder of the Eleatic School of philosophy.
The Eleatics rejected the logical (knowledge) validity of sense experience, and instead took standards of clarity and necessity to be the criteria of Truth. The concept of Truth is discussed and debated in several contexts. Some philosophers view the concept as basic, and unable to be explained in any terms.
Commonly, Truth is viewed as the correspondence of language or thought to an independent reality.
Identity is a fundamental metaphysical issue, the positions one takes on it has far-reaching implications on issues such as the mind-body interaction, personal identity, ethics and law.
Greeks took extreme positions on the nature of change. Parmenides denied change altogether, while Hera'Clitus argued that change was ubiquitous: "You cannot step into the same River twice."
A modern philosopher who made a lasting impact on the philosophy of identity was Leibniz (1 July 1646-Nov14,1716), a German polymath, whose "Law of the Indiscernability of Identicals" is still in wide use today. Leibniz, in philosophy, is most noted for his optimism in his conclusion that the Universe is, in a restricted sense, the best possible one that God could have created. His father died when he was 6 and from that point he was raised by his mother. His father had been a Professor of Moral Philosophy at the University of Leipzig, Germany, one of the World's oldest universities. The boy later inherited his father's personal library. He was given free access to it from the age of 7 enabling him to self study a wide variety of advanced philosophical and theological works. The books were written in Latin that led to his proficiency in the Latin language, which he achieved at the age of 12.
Famous alumni include Goethe, Ranke, Nietzsche, Wagner, Angela Merkel, Raila Odinga, Tycho Brahe, and 9 Nobel Laureates are associated with the University.
The earliest recorded Philosophy of Time was expounded by Egyptian thinker Ptah'Hotep (2650-2600 BC), who said, "Do not lessen the Time of following desire, for the wasting of time is an abomination to the spirit." The Vedas, the earliest texts on Indian philosophy and Hindu philosophy, dating back to the late 2nd millennium BC, describe its cosmology, in which the Universe goes through repeated cycles of creation, destruction, and rebirth, with each cycle lasting 4'320,000 years. Parmenides and Hera'Clitus, also wrote essays on the nature of Time. The Incas in South America and the Pre-Incas cultures regarded space and time as a single concept, named "Pacha." Plato, in "Timaeus," identified Time with the Period of Motion of the heavenly bodies, and space as that in which things come to be.
In the early century, the Muslim physicist Ibn Al-Haytham discussed space perception and its implications in his book "Book of Optics." In "tying the visual perception of space to prior bodily experience, he rejected the intuitiveness of spatial perception and, the autonomy of vision. Without tangible notions of distance and size for correlation, sight can tell us next to nothing about such things.
Other questions that Metaphysicians investigate are about the ways the World could have been. The term goes to Leibniz's theory of possible worlds. The actual World is regarded as merely one among an infinite set of logically possible Worlds, some nearer to the actual World and some more remote.
Cosmology is dealt with the World as the totality of all phenomena in space and time. It has had a broad scope and was founded in religion. It deals specifically with the origin of the Universe, its first cause, its necessary existence, its material components, and its ultimate reason for its existence and its purpose.
The nature of Matter was a problem in its own right in early philosophy. It was the material cause underlying a change in Aristotelian philosophy. The Greeks originally had no word for matter so Aristotle adapted the word for "wood" to this purpose. The idea that everything physical is made of the same basic substance holds up well under modern science, although it may be thought of more in terms of energy, a substance that endure a change in form, or transformation. Democritus, in conjunction with his mentor, Leucippus, conceived of an atomic theory some 24 centuries before it was accepted by modern science.
The nature of the Mind and its relation to the Body has been seen as more of a problem as science has progressed in its mechanistic understanding of the Brain and Body. Rene Descartes proposed substance dualism, a theory in which Mind and Body are essentially different, with the Mind having some of the attributes assigned to the Soul, creating a conceptual puzzle  about how the two interact.
Phineas Gage (1823-1860) was an American railroad foreman remembered for his strange survival of an accident in which a large iron rod was driven completely through his head, destroying much of his brain's left frontal lobe, and for that injury's reported effects on his personality and behavior over the remaining 12 years of his life -effects sufficiently profound that friends saw him as "no longer Gage."
His case influenced 19th-century discussion about Mind and Brain, and the 1st case to suggest the Brain's role in determining personality, and that damage to specific parts of the brain might induce specific personality changes. A report of his physical and mental condition shortly before his death implies that his most serious mental changes were temporary, so that in later life he was far more functional, and socially far better adapted, than in the years immediately following his accident. A social recovery hypothesis suggest that Gage's work as a stagecoach driver in Chile fostered this recovery by providing daily structure which allowed him to regain lost social and personal skills.
He was described before the accident as a perfectly healthy, strong and active young man, 26 years of age with excitable and active mental powers, able to endure great mental and physical labor.
On September 13, 1848, Gage was directing a work gang blasting rock while preparing the roadbed for the railroad South of the Town of Cavendish, Vermont. His attention was attracted by his men behind him and inadvertently bringing his head into line with the blast.  George was thrown onto his back and gave some brief convulsions  of the arms and legs, but spoke within a few minutes, walked with little assistant, and sat upright. About 30 minutes after the accident physician Edward H. Williams, arrive to the scene, he said; "I first noticed the wound upon the head, the pulsations of the brain were distinct. The top of the head appeared somewhat like an inverted tunnel, as if some wedge-shaped body had passed from below upward. During the time I was examining the wound, Gage was explaining to bystanders the manner in which he was wounded, then he got up and vomited and the effort pressed out about half a teacup of the brain, which fell upon the floor. Despite his own optimism, Gage's convalescence was long, difficult, and uneven. Though recognizing his mother and uncle on the morning after the accident, on the 2nd day he "lost control of his Mind, and became delirious." By the 4th day he was again rational, able to recognize his friends. At the 12th day he was semi-comatose, seldom speaking and answering only in monosyllables. The following days his strength decay, coma deepened; the globe of the left eye became protuberant with fungus and with infected brain tissue pushing out rapidly. At the 14th day the exhalations from the mouth and head were fetid. The fungi was controlled by cutting it out and cleaning the fetid liquid accumulated in the cavity. After weeks of further improvements, he started to entertain the idea that is was possible for him to recover. On the 24th day, Gage succeeded in raising himself up and took one step to his chair. One month later he was walking up and down stairs, and about the house, and in the street. He was uncontrollable at this point. He soon developed a fever and after a while he recovered again. 10 weeks after the accident he was able to return to his parent's home traveling in an enclosed carriage of the kind used for transportation of the insane. After a little while he was able to do a little work about the horses in the farm, feeding the cattle etc. After a mont there his mother told to the physician that his son's memory seemed somewhat impaired, though slightly enough that a stranger would not notice. His recovery was quite complete during the 4 years after the accident. In November 1849, the professor of Surgery at Harvard University brought Gage to Boston for several weeks to further medical research. Unable to return to his usual work he was for a time a kind of living museum exhibit at Barnum's American Museum in New York City. The for 18 months he worked for the owner of a stable and coach service in Hanover, New Hamp'Shire. In August 1852, Gage was invited to Chile to work as a long-distant stagecoach driver there, caring for the horses and often driving heavily laden and drawn by 6 horses on the Valparaiso-Santiago route. His health began to fail in in 1859 due to hardship and exposure. He went back to his mother house and after a brief period of resting and recovering and anxious to work he found a job with a farmer nearby. In 1860 Gage began to have epileptic seizures increasing in frequency and severity but he wanted to continue to work but he could not do much. In 1866, he had his final epileptic attack and died after convulsing day and night. His skull and his iron bar were claimed by the physician who treated him soon after the accident. After studying them, the surgeon deposited the iron bar and the skull in the Warren Museum.
Determinism is the proposition that every event, decision and action, is casually determined by an unbroken chain of prior occurrences.It holds that nothing happens that has not already been determined.
The principal consequence of the claim is that it posses a challenge to the existence of free will.
The problem of free will is whether rational agents exercise control over their own actions and decisions. Addressing this problem requires understanding the relation between freedom and causation, and determining whether the laws of nature are causally deterministic.
The ones who accept Free Will  but reject Determinism are called Libertarians, a term not to be confused with the political sense.
Metaphysics continues asking "why"where science leaves off.