Faculty of speech is the important trait of humans. When a newborn comes into the world, it announces itself by crying loudly. As it begins to grow under the constant vigil of its mother, it continuously makes unconscious efforts to speak. Parents are highly conscious about when their child will start speaking. Mothers joy know no bounds when it utters the first coherent word which is usually mom.
Other living beings have been incapable of large coherent repertoire of speech and instead rely on the use of other faculties to communicate to one another. It has taken the humans on higher plane than other animals.
Speech Is also two edged sword which when used judiciously is a powerful weapon and used without caution can do the irreparable damage. No physical weapon is more powerful than the speech.
Observe a person who is a dumb. Devoid of this faculty and you will realise his pain and helplessness. A grown up dumb person, despite knowing that he is unable to speak will try to speak, although only incoherent sounds issue from his mouth, along with the other gestures of hands and body.
Why does he continues to make this effort every time he has to convey something to others. May be there is a deep seated hope that speech, a natural trait, might issue from his mouth.
His thoughts are trapped like caged birds continuously hitting the cage wanting to be liberated. He cannot express so many of his thoughts which lay stifled inside his body.