The sky and water were lost in the clear line of the horizon.
As Poppy23 said, there's already a fairly clear line on this.
There is no clear line dividing public and private education.
There is no clear line between private thoughts and public property.
Often there is no clear line between the illusion and the reality of power.
The courts are beginning to look at this now, but there's no clear line.
"Stand away from him and give me a clear line of sight."
Why is there no clear European line on this point?
We tried very hard to lay down clear lines of responsibility.
More showed up, from the other direction, with a clear line of fire.