He advocates that parents should be reading to their children. It's a systematic approach to reading by raising your child's listening comprehension. If a child never hears a word used, the likelihood that they will recognize it in print is very small. Listening comprehension has to come before reading comprehension. The reason for reading to children is the same reason for talking to them.
Reading explains, reassures, informs, inspires and entertains children in a personal manner.
Trelease goes on to explain that at age 3 a child will learn 10 new words a day based simply on what the child hears, most of which won't come from flash cards or computers. Furthermore, by age 4 your child has already learned and understands two-thirds of the words they will use in daily life. The deck is already stacked before they ever get to kindergarten. Now that's not necessarily bad. In fact it's good, very good, if the child has been read to from infancy.