Finally we should note that the Lord commands every one of us in all the actions of our life to be faithful in our calling. For he knows that the human mind burns with restlessness, that it is swept easily hither and thither, and that its ambition to embrace many things at once is insatiable.
Therefore, to prevent that general confusion being produced by our folly and boldness, he has appointed to everyone his particular duties in the different spheres of life.
And, that no one might rashly go beyond his limits, he has called such spheres of life vocations, or callings.
Every individual’s sphere of life, therefore, is a post assigned him by the Lord that he may not wander about in uncertainty all the days of his life.
And so necessary is this distinction, that in his sight all our actions are measured by it, and often very differently from the judgment of human reason or philosophy.
—John Calvin