The philosophy of early Buddhism deals with psychology rather than with metaphysics.  It holds it profitable to analyze and discuss man’s mental constitution, because such knowledge leads to the destruction of false ideals and the pursuit of peace and insight.  Enquiry into the origin and nature of the external world is not equally profitable:  in fact it is a vain intellectual pastime.  Still in treating of such matters as sensation, perception and consciousness, it is impossible to ignore the question of external objects or to avoid propounding, at least by implication, some theory about them.  In this connection we often come upon the important word Dhamma (Sanskrit, Dharma).  It means a law, and more especially the law of the Buddha, or, in a wider sense, justice, righteousness or religion[420].  But outside the moral and religious sphere it is commonly used in the plural as equivalent to phenomena, considered as involving states of consciousness.  The Dhamma-sangani[421] divides phenomena into those which exist for the subject and those which exist for other individuals and ignores the possibility of things existing apart from a knowing subject.  This hints at idealism and other statements seem more precise.  Thus the Samyutta-Nikaya declares:  “Verily, within this mortal body, some six feet high, but conscious and endowed with mind, is the world, and its origin, and its passing away[422].”  And similarly[423] the problem is posed, “Where do the four elements pass away and leave no trace behind.”  Neither gods nor men can answer it, and when it is referred to the Buddha, his decision is that the question is wrongly put and therefore admits of no solution.  “Instead of asking where the four elements pass away without trace, you should have asked: 

  Where do earth, water, fire and wind,
  And long and short and fine and coarse,
  Pure and impure no footing find? 
  Where is it that both name and form[424]
  Die out and leave no trace behind?”

To that the answer is:  In the mind of the Saint.

Yet it is certain that such passages should not be interpreted as equivalent to the later Yogacara doctrine that only thought really exists or to any form of the doctrine that the world is Maya or illusion.  The Pitakas leave no doubt on this point, for they elaborate with clearness and consistency the theory that sensation and consciousness depend on contact, that is contact between sense organs and sense objects.  “Man is conceived as a compound of instruments, receptive and reacting[425]” and the Samyutta-Nikaya puts into the Buddha’s mouth the following dogmatic statement[426].  “Consciousness arises because of duality.  What is that duality?  Visual[427] consciousness arises because of sight and because of visible objects.  Sight is transitory and mutable:  it is its very nature to change.  Visible objects are the same.  So this duality is both in movement and transitory.”