But if you do want to give your text a flowing colour, there is an easy way of doing it.
- type text as usual (black letters on white background), make them bold, increase the size;
- make a screenshot of the text: Command+Shift+4 (⌘+⇧+4), image should appear on your Desktop as PNG file;
- create (import) a shape, give it gradient colour fill (option in Graphics inspector);
- import the screenshot and slide it over the shape;
- remove black text with Alpha - as you do it the flowing colour appears through the letters, 'filling' them.
And a nice touch: to give your letters a glowing effect add shadow to the screenshot and give it one of the colours of the gradient combination.
When finished group the screenshot and the shape behind it, print to PDF or JPEG and use it in your project/document (resize, crop or mask as needed).
In the example above for gradient fill I used Maraschino and Lemon from the Colour Palette (Viewer). The font is Minion Pro, 64 points.
Read also Transparent Text (Putting Image Inside Letters)