A turning point . . . I think

My mother used to issue a gentle warning every time I became opinionated. ''Don't be so positive, love. It's prudent to leave a small 'I-think' bridge in case you have to turn around.'' Her graceful line of retreat often saved me from more than a few awkward situations. I began to suggest, ever so casually, that Tyler do likewise.

This small grandson is quickly becoming a genuine ''I-think'' individual. He's also swiftly observant. Walking along the path by the brook, we both noticed that a kingfisher on a crosspole was top-heavy but precisely balanced. He was efficiently designed for his needs, we granted, and ''He'll get a minnow for his lunch, I think,'' Tyler speculated - to ensure the balance, I assumed.

He scuffed at a corroded lump of iron - an old spike that once held the track down. ''Papa-Bob says these will be very val'ble some day, Gocky. I think. . . . '' It weighed down his pocket. Straight ahead of us, a baby cottontail nibbled at clover. We proceeded softly, making no sudden moves that might startle the tiny bundle of brown fur. We saw his sensitive nose twitching, his mouth daintily munching. When he lowered his head to feed, paused, and his ears became suddenly alert, we froze, holding our breath. When the rabbit resumed his meal, too young to be wary for long, Ty went on ahead, stealthily getting within a yard of the baby. ''Hi,'' he whispered, extending a tentative hand. The rabbit was not buying. Caution seems to him the better part of valor. He needed open space between him and that human scent of which his mother had warned him. He leaped to one side, white powder-puff tail denoting alarm. And that's the last we saw of him before he was safe in the brush.

''You saw how close he let me get?'' Ty pleaded. ''Next time we'll be friends . . . I think. . . .'' All at once the child was conscious of this repeated need for bolstering conviction. ''I'm always saying that, Gocky: 'I think, I think!' ''

''So? What's wrong with thinking? Smart people like to leave a little bridge to come back on - in case they make a little mistake. Or want to go another way. . . .''

''Like the bunny just did?''

''Sort-of. But he goes more by instinct. That's a kind of command - like pushing a button.'' Tyler grins relief: Artoo-Detoo and the rest of those intergallactic characters make sense.

''Instinct told him to jump?''

''Right. It controls animals. Your rabbit didn't consider 'I'm going to jump' before he did. He simply obeyed instinct and jumped into the brier patch. People have the choice - to think, then jump or not jump.''

He was obviously mulling it over. A small snake appeared straight ahead, sunning on brown leaves. We both saw it the same instant and instinctively started to one side. ''It's OK, Gocky,'' my champion declared. ''It's only a hurtless garter snake . . . I think. . . .''

He looked at me sideways and grinned a little. He'd left a little bridge in which to get back to safe ground in case I needed some help.

Reflecting on this later, it seemed to me that small adventure was a turning point in Tyler's growing up. On that day he ceased to be a little child and took his first steps in becoming a thoughtful boy.