If we thoughtfully observe the human body we discover this wisdom in each organ, in each part. For instance, if we study the upper portion of the human thigh bone we find in it a network of cells beautifully constructed with a view to their purpose. No engineer of the present day would be able to produce these two columns, which bear the upper part of the human body with the smallest expenditure of matter and force.
Wisdom was implanted in the human body as long as the divine Spirits worked upon it. As a rule the physical body is looked upon as the lowest part of man, unjustly so, for the very greatest wisdom can be seen just in the physical body. Only through this wisdom is it possible for the physical body to withstand the attacks continually made upon it by the astral body, and so not break up before the time.
The pleasures and desires which hold sway in the physical body when tea and coffee, alcohol and so on are taken, all these are attacks of the astral body on the physical body, and especially on the heart. It has therefore to be so wisely constructed that these attacks can be withstood for decades. Of course the suitable form of the heart could only be discovered by subjecting it to many transformations.
Source: Rudolf Steiner – GA 100 – The Gospel of St. John – Lecture IV – Basle, 19th November 1907