Students of Rashi must bear in mind that Rashi could sometimes use universal principles applicable in all languages. This particularly applies to the meaning methods.

The synechdoche principle basically says that any language can use a good example to name an entire category. For example, in English,
• the word honey can mean anything sweet.
• Similarly bread can refer to any food.
• Man can refer to any person (male of female)
• day can refer to the entire 24 hour period
• heart can refer to the entire person as in e.g., (Ps 43)My heart yearns for you, God which really means My entire person yearns for you God

Applying this principle to Lv21-21 which presents the prohibition of Priests making offerings, no man of the seed of Aaron the priest, that hath a blemish, shall come nigh to offer the offerings of HaShem made by fire; he hath a blemish; he shall not come nigh to offer the bread of his G-d. we would translate as follows no man of the seed of Aaron the priest, that hath a blemish, shall come nigh to offer the offerings of HaShem made by fire; he hath a blemish; he shall not come nigh to offer the food / offerings of his G-d.

Advanced Rashi: Rashi actually uses two principles here:
• Synechdoche: The word Bread can refer to any food. Hence bread of God is translated as food of God.
• Symbolism: The phrase food of God refers to offered items that are consumed like food to trigger prophetic visions and the descent of Godly energy.
Here Food and fire consumed offerings have a common form and function: They both involve
• the destruction / consummation of items and
• they both involve renewed energy (Food provides physical energy while the offerings provide spiritual energy).