Noun
The plank, stone, or piece of timber, which lies under a door, especially of a dwelling house, church, temple, or the like; the doorsill; hence, entrance; gate; door.
Fig.: The place or point of entering or beginning, entrance; outset; as, the threshold of life.
Source: Webster's dictionaryIt is possible that mankind is on the threshold of a golden age; but, if so, it will be necessary first to slay the dragon that guards the door, and this dragon is religion. Bertrand Russell
Triumphant science and technology are only at the threshold of man's command over sources of energy so stupendous that, if used for military purposes, they can wipe out our entire civilization. Cordell Hull
It soon became obvious that we were but on the threshold of the discovery. Howard Carter
The hardest step is that over the threshold. Italian Proverb
The hardest step is over the threshold. Chinese Proverb
The most difficult mountain to cross is the threshold. Danish Proverb