[[Dear Sister, why can consecrated hermits miss daily or even Sunday Mass? If I make private vows as a hermit can I miss Sunday Mass in the name of eremitical hiddenness or stricter separation from the world?]]
Thanks for your questions. There are several posts written about attendance at Mass so I would suggest you check out the labels to the right and locate the pertinent posts under "Eucharistic Spirituality and Solitude". The answers are pretty straightforward. Consecrated (canonical) solitary hermits may miss Sunday Mass sometimes if the requirements of the silence of solitude make this necessary. The silence of solitude to which they are publicly committed is not only a way of describing the environment in which the hermit lives her life, but it is also the goal of her life, a particular way of describing fullness of authentic humanity in communion/union with God lived for the sake of others. While it would be relatively rare for hermits to miss Sunday Mass the presence of the reserved Eucharist makes it possible for the hermit to maintain her link with the parish liturgy while also living into the silence of solitude in more profound ways. Still, missing Mass on Sundays is possible because the canonical hermit is legitimately committed (i.e., committed in law) to eremitical silence of solitude beyond her baptismal obligations.
As you can guess, this decision to miss Mass, especially when it extends several weeks or more because of the claims of the silence of solitude will be carefully discerned and discussed with one's Director/delegate and/or one's Bishop. Because the Eucharistic celebration is such a high value for the canonical hermit, to miss more than occasionally without really good and well-discerned reasons is ill-advised at best. On the other hand, missing daily Mass is more common and understandable; Religious are not required to attend Mass every day though they are required to make Eucharistic spirituality the heart of their lives. For canonical hermits daily Mass may truly interfere with the requirements of silence and solitude or the silence of solitude.
Privately vowed hermits are in a different position because their vows are an entirely private matter. Publicly such hermits are, of course, canonically bound to the same rights and obligations as any baptized Catholic; no public profession grants or binds with additional (and sometimes differing) rights and obligations as occurs in the life of the canonical hermit. This is why the Church makes clear a lay person who lives as a hermit with private vows alone (or none at all) are still lay persons --- persons baptized into the rights and obligations of the laity (laos =People). Neither would a hermit in the baptized state alone (private vows do not change this) have a legitimate (canonical) superior/delegate with whom such a matter could be discerned and by whom it might be permitted or even encouraged. (A good spiritual director can and will help with discernment in this case but does not have the authority to allow or give permission for such a thing.) Since you would not be publicly admitted to nor bound canonically (legally) by the silence of solitude (or the hiddenness which is derivative of this), or any of the other elements of canon 603 none of these can supersede your baptismal rights and obligations. Since baptism is associated with the public (legal) obligation to attend Mass every Sunday unless illness or some similar emergency intervenes, private commitments (which are of a different level than public commitments) cannot change these foundational rights or obligations.
Another piece of this answer is a consideration of the meaning of the phrase "the world" in "stricter separation from the world." "The world" does not mean the entirety of created reality outside the hermitage; instead it means that which is resistant to Christ or which promises fulfillment apart from Christ. In this sense "the world" cannot be said to include one's parish or (more especially) Sunday Mass! Only secondarily can it mean dimensions of God's good creation which are not resistant to Christ. In light of this we must point out that if one is taking it upon oneself to miss Mass in the name of entirely private commitments one may really be guilty of acting in a particularly selfish (individualistic) and thus, an entirely worldly way!! Finally, the idea of eremitical hiddenness is, as I have written recently, a derivative value which stems from the canonical elements of stricter separation and the silence of solitude. cf., Hiddenness as a derivative or Subordinate Value for the Hermit. Hermits do not make vows of hiddenness nor is this value even mentioned in canon 603. To privilege this vague term over one's public obligations is a seriously misguided practice; it seems individualistic to me, and therefore, "worldly." Meanwhile, since you are not canonically (legally) obligated to stricter separation from the world you cannot privilege this over the values and practices you are canonically obligated to by virtue of your baptism.
(Quote continues:) The rights that came with canonical standing include the right to call myself a Catholic and/or Diocesan Hermit, the right to wear a habit and cowl (both right and obligation attached to perpetual profession), and the right to style myself as Sister. In other words, I was given and assumed the right to live this life and serve my brothers and sisters in this way in the name of the Church. ]] cf., Followup on Hermits and Sunday Mass Attendance In instances where I need to absent myself from public Eucharist for a more extended period, I might then need to have a priest come into the hermitage to say Mass periodically. This would also be something (a right or obligation) canon law speaks to and my bishop or delegate could require and/or permit.