Trinity. What does the Bible say?

"As long as I can remember, I have always been able to read. I do not remember how I learned this skill. Probably, I learned the alphabet and simple words using a primer. I consider myself in debt to it,... as it laid the foundations of reading that I use to this day... This little book is also a primer, mastering which you will continue to learn further. It will not provide you with all the knowledge. It will simply help you take your first steps. From it, you will learn the basics of the doctrine of the Trinity. The book will relieve you of the uncertainty that you may feel when encountering this profound topic; moreover, you will learn enough to advance in those areas of knowledge where you previously did not dare to start."