"It is in reconciling the similarity of the experience with the lengthening out of the time process that you achieve an understanding of yourself, and of how to handle the influences"........of Uranus, Neptune, etc. as they travel through the signs and houses and over the planets in the natal chart. He feels that, for instance, a Uranus transit to the Sun is essentially the same as a Saturn transit or even a Mars transit. The difference resides in the time the planet remains in one place (conjunct, or in aspect to, a natal planet or point).
Our bodies and minds are naturally conditioned to the fast transits of the inner planets and the Moon, even to relatively fast transits of Jupiter and Mars. By adulthood we have experienced several of these and instinctively, or subconsciously respond naturally to them. When we experience a conjunction or hard aspect involving one of the outer planets, lasting for much longer, it has to seem somehow different, though not in the ways we might first suppose: Saturn's influence is said to be restrictive or severe, Uranus brings the quirky and unexpected, Pluto is the transformer....etc. Mr Lewi theorised that these transits feel different because they last so much longer, and in truth, the influence itself is much the same in each case.
From chapter 12 (page 376) The Grand Strategy of Living - part 1: The Nature and Meaning of the Planets
"It used to be stated, or implied, in the older astrological texts, that each of the Planets had a different quality, character, or tone, because of something inherent in its nature, Thus Saturn might have been said to have the quality of iron, hardness, weight; the character of sobriety or gloom; the tone of G-sharp Minor below middle C, or of the rumble of distant thunder. Mars might have been said to have the quality of hot steel, the character of courage or recklessness, and the tone of an awakening bugle. Whether these attributes emanated from the physio-chemical structure of the planets, which caused them to emit rays of a certain quality, or from other causes, was not clarified.That outer planets' transits might have more to do with the length of their stay than with the traditional definition of the nature of that planet is a new idea to me, but not an outlandish one. Pluto, Uranus and Saturn bring changes, their motion is so slow as to make a visit from them to natal planets something unusual in itself. Neptune is not as easy to see as a bringer of general change though - change of attitude perhaps, rather than changes in outside circumstances.
The premise seems to have been that each Planet had a quality inherent in itself, differentiating it and its influence from that of other Planets because of this self-contained quality.
Over a long period of study, in contact with numerous charts viewed experimentally and clinically, I have come to the conclusion that, so far as their astrological influence is concerned, the Planets do not differ in inherent quality. We know from the astronomers, physicists, spectrum-analysts, and chemists that the physical structure of the Planets is different, quantitatively, with respect to the percentages in which the elements are found in them and their atmospheres; and qualitatively, with respect to their stages of hotness, coolness, age, youth, formedness or non-formedness. It is possible that these differences do bear on their astrological influence.
However, consistent observation of planetary effects in a very large number of charts leads me to the conclusion that, whether or not Planets differ in their inherent character, their chief observable difference as they act in the chart is traceable directly to the difference in the rate of motion with which they pass through the Vitasphere......" (Grant Lewi called the natal chart the Vitasphere.)"Once we disabuse our minds of the idea that Planets differ in quality, and base our view of the chart on their differences in rate of motion, we come to grips with the basic realities of the Vitasphere, with the meaning of planetary influences in the forming of character and the timing of opportunity."
It's quite difficult to turn off the specific astrological definitions for individual outer planets as stored in memory. I still tend to fall back on traditional interpretations. Even so, Grant Lewi's idea is one to keep in mind; i.e. that Saturn transits need not be severe or restrictive, just different; Uranus need not bring eccentricities or the unexpected just a feeling of things not as usual; Pluto need not be the dark, initially painful bringer of transformation, but will, for sure, herald change of some kind depending on personal background and circumstance.