That is hard advice for a mind to take. The not-self is deeply disturbed by anything it cannot see, and Neptune's veil hides limitations as well as gifts, which is how this placement can become a place of self-deception and even abuse. The person who insists on seeing through the veil ends up seeing what they want to see. The person who surrenders to it learns, over a lifetime, what surrender actually is.
On the Personality Side
Your Personality Neptune is the conscious veil: the area of life where you experience illusion, longing, spiritual yearning and a persistent inability to get a clear picture. The gate names the subject. People often describe it as the thing they keep reaching for and can never quite grasp, and the reaching is the not-self at work.
On the Design Side
Your Design Neptune is where your body is veiled from itself. It is the part of your form and your behaviour you genuinely cannot see, and it is a mistake to try. Other people sometimes glimpse this in you, and when they describe it the description feels both true and impossible to verify.
A Generational Planet
Neptune takes about one hundred and sixty-five years to go round the wheel, spending roughly fourteen years in each sign, so it marks whole generations more than it marks individuals. Human Design counts it among the transpersonal planets for this reason, and part of what your Neptune describes is an illusion your entire cohort shares.
Reading It In Your Chart
Find the Neptune glyph on each side and note the gate. Then do something you will not be asked to do with any other placement: read the gate, notice the potential it describes, and consciously decline to chase it. The work with Neptune is trust, patience and intuition rather than analysis. What is behind the veil arrives on its own schedule, and the people who receive it are the ones who stopped demanding to see it first. Human Design groups Neptune with Uranus and Pluto as the three great lifelong themes of learning, and Neptune's theme is the nature of letting go.