Mind, Heart, Soul and Brain....

My friend sent me a quote "The Mind knows nothing, and can speak,
the heart knows everything but cannot speak."
Which I honestly thought was lame. May be I am poetically challenged. Someone told me yesterday on my rant on Valentine’s Day that rational thinking is always no good, and we should leave something as unknowns 'cause we like some mystery with our mayonnaise in our sandwiches.
Me being myself couldn’t resist thinking logically about the above quotation. For this quotaion to be valid there should be some difference between heart and mind. So lets dig into those definitions.
Heart
She obviously didn’t mean the muscular organ which regulates the blood supply around the body, but she meant what Wikipedia describes as "in the Bible, and in much later literature, the heart is used as a metaphor to refer to the moral core of a human being including the intellect and not just the emotions." So the moral core knows everything but cannot speak! Isn’t moral core equivalent to one’s conscience? Isn’t conscience your guide? How can it guide if it can’t speak to you?
Mind
Again Wikipedia says "The mind is the term most commonly used to describe the higher functions of the human brain, particularly those of which humans are subjectively conscious, such as personality, thought, reason, memory, intelligence and emotion. Although other species of animals share some of these mental capacities, the term is usually used only in relation to humans.” Ironically she says that mind knows nothing, in fact it knows everything and 'speaks' to you too...

When we are at it let me talk about Brain and Soul too...
Brain
Brain is the central processing unit (CPU) and controls all the basic and advanced funtions of the body. If brain 'dies' the 'body' dies immediately or pretty soon too. Brain is more a biological definition and mind is more philosophical definition. For me both definitions are interchangeable. Is a brainless person a mindless person too? If you have a high IQ, you must have an active brain, and on the other hand if you have a high EQ (Emotional Quotient) you have a good mind.
Soul
Soul is typically a religious concept. It is your inner self, which can’t be destroyed, part of ‘God’, which defines the essence of life. I don’t believe in any soul at all.

In one sense all these four concepts can be interchanged and can be used as you please. One rule of thumb is when these words, especially mind and soul appear in one sentence; the sentence can usually be ignored and would as a rule contains "feel good" bull.