Lollipops

There's a lovely text called Local Fields by J.W.S. Cassels, which is not a field guide to regional farmland but an introduction to p-adic numbers. His preface begins with a quote:

My heart is inditing a good matter. Psalm 45.

Before listing the contents of the book he issues a warning:

Paragraphs which can be omitted at a first reading are marked with an asterisk. But if you do skip them, then you miss some of the lollipops.