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Fourthly, many striking results, both great and small, may be produced by an extension of a principle whicfi may be described as that of s ^ation' c sympathetic vibration. Illustrations taken from the physical plane seem generally to misrepresent rather than elucidate astral phenomena, because they can never be more than partially applicable ; but the recollection of two simple facts of ordinary life may help to make this important branch of our subject clearer, if we are careful not to push the analogy further titan it will hold good.
n It is well known that if one of the wires of a harp be made to vibrate vigorously, its movement will call forth sympathetic vibrations in the corresponding strings of any number of harps placed round it, if they are timed to exactly the same pitch. It is also well known that when a large body of soldiers crosses s a suspension bridge it is necessary for them to break step, since the perfect regularity of their ordinary march would set up a vibration in the bridge which Aould be intensified by even- step thcy.took until the £>oint of resistance of the iron was passed, when the whole structure would fly to pieces*
With these two analogies in our minds (never forgetting that they are only partial ones) it may seem more, comprehensible