When the caravans in the desert are in want of water, they are accustomed to send a camel with its rider some distance in advance.
Then, after a time, follows another & then at a short interval another.
As soon as the first man finds water, almost before he stoops down to drink, he shouts aloud, "Come!"
The next man hearing the call repeats it, "Come!" The nearest man again takes up the call, "Come!" until the surrounding desert echoes with the word "Come!"
This is the great invitation word of the Gospel, come! come! COME!
- Gospel Stories for the Young. (moreillustrations.com)
John 4:13-14 (PHILLIPS): Jesus said to her, “Everyone who drinks this water will be thirsty again. But whoever drinks the water I will give him will never be thirsty again. For my gift will become a spring in the man himself, welling up into eternal life.”