The sun works on the vine through photosynthesis.  Meanwhile, below ground, the roots are pulling in from soil and sub-soil (limestone especially, but also clays and gravels) the nourishment which gives the vines their vigour and determines their character.  The elements assimilated through the roots have their effect on the fertility of the plant and the quality of its wines.

Research going back thirty years has revealed the crucial importance of trace elements.  And more recent fundamental and applied research has concentrated on the role played by living organisms in the soil, both macro-organisms visible to the naked eye (insects and invertebrates as well as the roots of the vines themselves) and micro-organisms (amoebae, algae, fungi, and bacteria.)  Millions, if not billions, of living micro-organisms are contained in a single gram of soil.
The lesson to be learned here is that this sensitive complex of living organisms is a precious heritage whose vitality it is our duty to protect and nurture.  As a result, our ideas on the best way to treat the soil and sub-soil have undergone radical revision following careful and minute study. Minimum impact is now the goal and modern techniques of viticulture reflect this ideal.

After the first mildew attacks in the 19th century, all the wine-growing regions had recourse to copper-based fungicides ("Bordeaux mixture") and no modern replacement has yet been found for these.  Nitrates and potash were used as fertilisers.
Whatever the source of these chemicals, Burgundian viticulture today tends more and more towards low-input methods.  The substances employed and the manner of their application are becoming increasingly subject to strict regulation.  The object, without question, is to produce better wines (better, too, for the health of the drinker) but also to guarantee to future generations the continuing capacity of the soil to maintain the personality of the terroir and the cru.
As in the fable, the treasure is here in the soil. It is our buried treasure, to be protected against dangers from outside, erosion for example, that can rob it of its natural character.  Aeons of time have gone into its creation, while our acquaintance with it has been brief.  But the Burgundy of today knows how to preserve this precious treasure to hand it on to future generations.