By way of a prelude.

By way of introduction, in advance; = preliminarily, adv. Frequently with to.

As a preliminary or introductory step.

In a preliminary manner; by way of introduction; to begin with.

in a prefatory manner; by way of a preface, in a preface.

in a prelusive manner; by way of prelude.

In an introductory manner; by way of introduction.

as an introduction.