The Lipps-Meyer law, named for Theodor Lipps (1851-1914) and Max Friedrich Meyer (1873-1967), hypothesizes that the closure of melodic intervals is determined by "whether or not the end tone of the interval can be represented by the number two or a power of two", in the frequency ratio between notes (see octave).
"The 'Lipps-Meyer' Law predicts an 'effect of finality' for a melodic interval that ends on a tone which, in terms of an idealized frequency ratio, can be represented as a power of two."
Thus the interval order matters -- a perfect fifth, for instance (C,G), ordered <C,G>, 2:3, gives an "effect of indicated continuation", while <G,C>, 3:2, gives an "effect of finality".
This is a measure of interval strength or stability and finality. Notice that it is similar to the more common measure of interval strength, which is determined by its approximation to a lower, stronger, or higher, weaker, position in the harmonic series.
The reason for the effect of finality of such interval ratios may be seen as follows. If is the interval ratio in consideration, where is a positive integer and is the higher harmonic number of the ratio, then its interval can be determined by taking the base-2 logarithm (3/2=7.02 and 4/3=4.98). The difference of these terms is the harmonic series representation of the interval in question (using harmonic numbers), whose bottom note is a transposition of the tonic by n octaves. This suggests why descending interval ratios with denominator a power of two are final. A similar situation is seen if the term in the numerator is a power of two.