Any accidental coincidence of events, such as meeting a person at a particular foreign resort, and any insignificant resemblance between objects, sounds, etc., may thus supply a path, so to speak, from fact to dream-fancy.
In our waking states these innumerable paths of association are practically closed by the supreme energy of the coherent groups of impressions furnished us from the world without through our organs of sense, and also by the volitional control of internal thought in obedience to the pressure of practical needs and desires.

In dream-life both of these influences are withdrawn, so that delicate threads of association, which have no chance of exerting their pull, so to speak, in our waking states, now make known their hidden force.

Little wonder, then, that the filaments which bind together these dream-successions should escape detection, since even in our waking thought we so often fail to see the connection which makes us pass in recollection from a name to a visible scene or perhaps to an emotional vibration.
It is worth noting that the origin of an association is often to be looked for in one of those momentary half-conscious acts of waking imagination to which reference has already been made.

A friend, for example, has been speaking to us of some common acquaintance, remarking on his poor health.

The language calls up, vaguely, a visual representation of the person sinking in health and dying.