Justus von Liebig Quote

When a power of nature, invisible and impalpable, is the subject of scientific inquiry, it is necessary, if we would comprehend its essence and properties, to study its manifestations and effects. For this purpose simple observation is insufficient, since error always lies on the surface, whilst truth must be sought in deeper regions.

Familiar Letters on Chemistry, Letter I (pp. 16-17), Walton & Maberly. 1859