Accumulation of similar or compatible elements appears to be the law of Nature. This is what accounts for formation of seas and oceans. Individually the metal particles lie unnoticed in the soil. However, wherever they are gathered, their force of affinity compounds exponentially and leads to formation of huge repository of that particular substance. The gigantic mines of metals and minerals evince this fact. Similar is the case with superposing of sound waves etc. The cycle of their circular motion and recurrence with further superimposition of similar thought waves creates a subtle energy field in the etheric expansion that widens and affects more and more people having even slightest receptivity to those thoughts, with its larger and sharper reach. This is why the books we read, the ambience we live in most of the time, or the people we interact with, indirectly influence our thinking and tendencies. This is how the company of drunkards produces more drunkards, that of thieves makes others thieves and so on; this is how criminals form stout gangs. This is how the inspiring proximity of saints, great personalities, or sagacious thoughts enlightens and elevates many others.
What kinds of thought waves influence one and to what extent? This depends upon what his mind is prepared for and what are its own intrinsic inclinations and aspirations. Radio stations or satellite sites broadcast/transmit varieties of programs, but our radio or television sets receive only those for what they are tuned. Our minds are also like antennas or receiving stations for thought waves they are naturally tuned or vigorously trained for. Good people with alert mind feel some kind of repulsion from cruel, cunning or debased people; whereas the magnetism of morally pure, elevated and kind-hearted personalities often attracts them. Contrary is the case with people having mental vices, evil characters or perverse tendencies.